reading about cardinality - uni- · pdf filereading about cardinality ... wim van dooren a,...

129
Reading About Cardinality Matthew Inglis Mathematics Education Centre Loughborough University

Upload: vophuc

Post on 26-Feb-2018

217 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Reading About Cardinality

Matthew InglisMathematics Education CentreLoughborough University

Page 2: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Plan

• Students find cardinal numbers difficult, but why?

• Existing explanations: theory of conceptual change.

• How do ‘strong’ and ‘weak’ students learn about cardinal arithmetic from text?

• Can mathematical reading strategies be improved?

Page 3: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Cardinal Numbers

• Cardinal numbers are known to be hard for students to understand (e.g., Borasi, 1984; Duval, 1983; Fischbein, Tirosh & Hess, 1979; Fischbein, Tirosh & Melamed, 1981; Tall, 1980, 1981, 2001a, 2001b; Tirosh, 1985).

• Traditionally understood from a “conceptual change” perspective.

• Goal of the talk: to argue that this should be supplemented by a “many students don’t (but can) read effectively” perspective.

Page 4: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

• The conceptual change account of learning posits an analogous process to Kuhnian paradigm shift in the philosophy of science (e.g. Vosniadou, 2001).

Page 5: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

• The conceptual change account of learning posits an analogous process to Kuhnian paradigm shift in the philosophy of science (e.g. Vosniadou, 2001).

• When new knowledge comes into conflict with existing knowledge major reorganisation is required, referred to as conceptual change.

Page 6: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

• The conceptual change account of learning posits an analogous process to Kuhnian paradigm shift in the philosophy of science (e.g. Vosniadou, 2001).

• When new knowledge comes into conflict with existing knowledge major reorganisation is required, referred to as conceptual change.

• Paradigmatic example: children learning about the shape of the earth.

Page 7: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

Straatemeier et al. (2008)

Page 8: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

Straatemeier et al. (2008)

Page 9: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

Straatemeier et al. (2008)

Page 10: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

Straatemeier et al. (2008)

Page 11: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change

Straatemeier et al. (2008)

Page 12: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and CardinalityMajor differences between students’ existing understanding of how numbers behave and how cardinal numbers behave.

@0 = 2 · @0

@0 = @0 + 1

Page 13: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and CardinalityMajor differences between students’ existing understanding of how numbers behave and how cardinal numbers behave.

@0 = 2 · @0

@0 = @0 + 1

n < 2n

n 6= n+ 1

Page 14: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and CardinalityMajor differences between students’ existing understanding of how numbers behave and how cardinal numbers behave.

@0 = 2 · @0

@0 = @0 + 1

Major differences between “infinity” and cardinality:

n < 2n

n 6= n+ 1

Page 15: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and CardinalityMajor differences between students’ existing understanding of how numbers behave and how cardinal numbers behave.

@0 = 2 · @0

@0 = @0 + 1

Major differences between “infinity” and cardinality:

limx!3�

1

x� 3= �1

n < 2n

n 6= n+ 1

Page 16: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and CardinalityMajor differences between students’ existing understanding of how numbers behave and how cardinal numbers behave.

@0 = 2 · @0

@0 = @0 + 1

Major differences between “infinity” and cardinality:

limx!3�

1

x� 3= �1 lim

x!3+

1

x� 3= 1

n < 2n

n 6= n+ 1

Page 17: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and CardinalityMajor differences between students’ existing understanding of how numbers behave and how cardinal numbers behave.

@0 = 2 · @0

@0 = @0 + 1

Major differences between “infinity” and cardinality:

limx!3�

1

x� 3= �1 lim

x!3+

1

x� 3= 1

What is this? Isn’t subtraction undefined?

n < 2n

n 6= n+ 1

Page 18: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and Cardinality

• Basic idea of the conceptual change approach is that you have to reconstruct your existing knowledge of numbers to account for these strange new properties.

Page 19: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and Cardinality

• Basic idea of the conceptual change approach is that you have to reconstruct your existing knowledge of numbers to account for these strange new properties.

• This is very difficult.

Page 20: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and Cardinality

• Basic idea of the conceptual change approach is that you have to reconstruct your existing knowledge of numbers to account for these strange new properties.

• This is very difficult.

• But... university-level students are really experienced at changing their conceptualisation of number.

Page 21: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Conceptual Change and Cardinality

• Basic idea of the conceptual change approach is that you have to reconstruct your existing knowledge of numbers to account for these strange new properties.

• This is very difficult.

• But... university-level students are really experienced at changing their conceptualisation of number.

• For example: the “Kuhnian revolution” from naturals to rationals.

Page 22: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number BiasChildren (and adults) struggle with fractions, in part because of interference from natural number knowledge.

Page 23: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

Which is bigger?

Children (and adults) struggle with fractions, in part because of interference from natural number knowledge.

Page 24: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

Which is bigger?

Children (and adults) struggle with fractions, in part because of interference from natural number knowledge.

7

8

5

8

Page 25: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number BiasChildren (and adults) struggle with fractions, in part because of interference from natural number knowledge.

Page 26: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

Which is bigger? 3

34

3

21

Children (and adults) struggle with fractions, in part because of interference from natural number knowledge.

Page 27: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

Which is bigger? 3

34

3

21

Seen as bigger because 34 > 21

Children (and adults) struggle with fractions, in part because of interference from natural number knowledge.

Page 28: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

Which is bigger? 3

34

3

21

Seen as bigger because 34 > 21

Children (and adults) struggle with fractions, in part because of interference from natural number knowledge.

We all have this bias, but (mostly) have successfully learnt to inhibit it

Page 29: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

The natural number bias and magnitude representation in fractioncomparison by expert mathematicians

Andreas Obersteiner a,b,*, Wim Van Dooren a, Jo Van Hoof a, Lieven Verschaffel aaCenter for Instructional Psychology and Technology, Katholieke Universiteit Leuven, Dekenstraat 2, Box 3773, 3000 Leuven, BelgiumbHeinz Nixdorf-Stiftungslehrstuhl für Didaktik der Mathematik, TUM School of Education, Technische Universität München, Marsstr. 20e22, 80335München, Germany1

a r t i c l e i n f o

Article history:Received 19 December 2012Received in revised form23 May 2013Accepted 26 May 2013

Keywords:Rational numbersWhole number biasComponential representationHolistic representationIntuitive reasoning

a b s t r a c t

When school students compare the numerical values of fractions, they have frequently been found to bebiased by the natural numbers involved (e.g., to believe that 1/4 > 1/3 because 4 > 3), thereby consid-ering fractions componentially as two natural numbers rather than holistically as one number. Adultstudies have suggested that intuitive processes could be the source of this bias, but also that adults areable to activate holistic rather than componential mental representations of fractions under some cir-cumstances. We studied expert mathematicians on various types of fraction comparison problems togain further evidence for the intuitive character of the bias, and to test how the mental representationsdepend on the type of comparison problems. We found that experts still show a tendency to be biased bynatural numbers and do not activate holistic representations when fraction pairs have common nu-merators or denominators. With fraction pairs without common components, we found no naturalnumber bias, and holistic representations were more likely. We discuss both findings in relation to eachother, and point out implications for mathematics education.

! 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Amply research has shown that students frequently strugglewith learning of rational numbers in general and with under-standing the concept of fractions in particular (e.g., Behr,Wachsmuth, Post, & Lesh, 1984; Iuculano & Butterworth, 2011;Mazzocco & Devlin, 2008; Sowder, 1988; Stafylidou & Vosniadou,2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011;Vamvakoussi & Vosniadou, 2004). A common error is to considera fraction as two separate natural numbers rather than as onenumber. This becomes explicit in fraction comparison problems,when decisions are based on comparing the components separatelyrather than on comparing the holistic fraction values. On suchproblems, students are frequently biased by the natural numbersthat make up the fractions (Meert, Grégoire, & Noël, 2010b; VanHoof, Lijnen, Verschaffel, & Van Dooren, 2013). For example, theybelieve that 1/4 is larger than 1/3 because 4 is larger than 3.

We address three issues that are not sufficiently studied byprevious research. The first one refers to the source of this

“natural number bias” on fraction comparison problems. As thebias has been found in adults, it has been concluded that intuitiveprocesses are the source of the bias. This would imply that it is notpossible to completely overcome it, even for people who have avery deep understanding of fractions, such as expert mathema-ticians. We therefore studied these people to gain further evi-dence for the intuitive character of the natural number bias. Thesecond issue concerns the generalizability of the natural numberbias in fraction comparison. So far, mainly special cases of com-parison problems, namely fraction pairs with common numera-tors or common denominators, were used as stimuli, so that it isunclear whether the bias occurs in fraction comparisons in gen-eral. The third issue is the question whether fractions canmentally be represented as integrated wholes rather than com-ponentially as two natural numbers. This issue is related to thenatural number bias, because it is possible that the bias occursonly when people use componential representations of fractionsbut not when they use holistic representations. Previous studieshave revealed that holistic representations are possible for certainfractions that people are presumably very familiar with (such as1/2), but there is very limited evidence that this is also possiblefor less well-known fractions. In the following, we elaborate onthe rationales and the available evidence for the three issuesraised here.

* Corresponding author. Arcisstr. 21, 80333 München, Germany. Tel.: !49 89 28925396.

E-mail address: [email protected] (A. Obersteiner).1 Present affiliation.

Contents lists available at SciVerse ScienceDirect

Learning and Instruction

journal homepage: www.elsevier .com/locate/ learninstruc

0959-4752/$ e see front matter ! 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.learninstruc.2013.05.003

Learning and Instruction 28 (2013) 64e72

Page 30: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

The natural number bias and magnitude representation in fractioncomparison by expert mathematicians

Andreas Obersteiner a,b,*, Wim Van Dooren a, Jo Van Hoof a, Lieven Verschaffel aaCenter for Instructional Psychology and Technology, Katholieke Universiteit Leuven, Dekenstraat 2, Box 3773, 3000 Leuven, BelgiumbHeinz Nixdorf-Stiftungslehrstuhl für Didaktik der Mathematik, TUM School of Education, Technische Universität München, Marsstr. 20e22, 80335München, Germany1

a r t i c l e i n f o

Article history:Received 19 December 2012Received in revised form23 May 2013Accepted 26 May 2013

Keywords:Rational numbersWhole number biasComponential representationHolistic representationIntuitive reasoning

a b s t r a c t

When school students compare the numerical values of fractions, they have frequently been found to bebiased by the natural numbers involved (e.g., to believe that 1/4 > 1/3 because 4 > 3), thereby consid-ering fractions componentially as two natural numbers rather than holistically as one number. Adultstudies have suggested that intuitive processes could be the source of this bias, but also that adults areable to activate holistic rather than componential mental representations of fractions under some cir-cumstances. We studied expert mathematicians on various types of fraction comparison problems togain further evidence for the intuitive character of the bias, and to test how the mental representationsdepend on the type of comparison problems. We found that experts still show a tendency to be biased bynatural numbers and do not activate holistic representations when fraction pairs have common nu-merators or denominators. With fraction pairs without common components, we found no naturalnumber bias, and holistic representations were more likely. We discuss both findings in relation to eachother, and point out implications for mathematics education.

! 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Amply research has shown that students frequently strugglewith learning of rational numbers in general and with under-standing the concept of fractions in particular (e.g., Behr,Wachsmuth, Post, & Lesh, 1984; Iuculano & Butterworth, 2011;Mazzocco & Devlin, 2008; Sowder, 1988; Stafylidou & Vosniadou,2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011;Vamvakoussi & Vosniadou, 2004). A common error is to considera fraction as two separate natural numbers rather than as onenumber. This becomes explicit in fraction comparison problems,when decisions are based on comparing the components separatelyrather than on comparing the holistic fraction values. On suchproblems, students are frequently biased by the natural numbersthat make up the fractions (Meert, Grégoire, & Noël, 2010b; VanHoof, Lijnen, Verschaffel, & Van Dooren, 2013). For example, theybelieve that 1/4 is larger than 1/3 because 4 is larger than 3.

We address three issues that are not sufficiently studied byprevious research. The first one refers to the source of this

“natural number bias” on fraction comparison problems. As thebias has been found in adults, it has been concluded that intuitiveprocesses are the source of the bias. This would imply that it is notpossible to completely overcome it, even for people who have avery deep understanding of fractions, such as expert mathema-ticians. We therefore studied these people to gain further evi-dence for the intuitive character of the natural number bias. Thesecond issue concerns the generalizability of the natural numberbias in fraction comparison. So far, mainly special cases of com-parison problems, namely fraction pairs with common numera-tors or common denominators, were used as stimuli, so that it isunclear whether the bias occurs in fraction comparisons in gen-eral. The third issue is the question whether fractions canmentally be represented as integrated wholes rather than com-ponentially as two natural numbers. This issue is related to thenatural number bias, because it is possible that the bias occursonly when people use componential representations of fractionsbut not when they use holistic representations. Previous studieshave revealed that holistic representations are possible for certainfractions that people are presumably very familiar with (such as1/2), but there is very limited evidence that this is also possiblefor less well-known fractions. In the following, we elaborate onthe rationales and the available evidence for the three issuesraised here.

* Corresponding author. Arcisstr. 21, 80333 München, Germany. Tel.: !49 89 28925396.

E-mail address: [email protected] (A. Obersteiner).1 Present affiliation.

Contents lists available at SciVerse ScienceDirect

Learning and Instruction

journal homepage: www.elsevier .com/locate/ learninstruc

0959-4752/$ e see front matter ! 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.learninstruc.2013.05.003

Learning and Instruction 28 (2013) 64e72

Page 31: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

Resp

onse

Tim

e (ms

)

1400

1600

1800

2000

2200

2400

GroupCongruent Incongruent

3/34 v 3/217/8 v 5/8

Page 32: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

• Students who meet cardinality have successfully negotiated the shift from naturals to integers, from integers to rationals, from rationals to reals, and from reals to complex numbers.

Page 33: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

• Students who meet cardinality have successfully negotiated the shift from naturals to integers, from integers to rationals, from rationals to reals, and from reals to complex numbers.

• They seem to do this by successfully inhibiting (not replacing) prior knowledge structures.

Page 34: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Natural Number Bias

• Students who meet cardinality have successfully negotiated the shift from naturals to integers, from integers to rationals, from rationals to reals, and from reals to complex numbers.

• They seem to do this by successfully inhibiting (not replacing) prior knowledge structures.

• It seems like another change in the meaning of “number” shouldn’t be too surprising to them?

Page 35: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Rationale

• We were interested in learning about how ‘strong’ and ‘weak’ students would approach learning about cardinal arithmetic.

Page 36: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Rationale

• We were interested in learning about how ‘strong’ and ‘weak’ students would approach learning about cardinal arithmetic.

• What would confuse them?

Page 37: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Rationale

• We were interested in learning about how ‘strong’ and ‘weak’ students would approach learning about cardinal arithmetic.

• What would confuse them?

• Would they get hung up with aspects of cardinal arithmetic that conflict with their prior knowledge of arithmetic?

Page 38: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Method• Recruited 20 students: 12 ‘good’ students (scored

over 70% in their first year set theory module), and 8 ‘weak’ students (scored less than 60%);

• All had taken a set theory module which introduced cardinal numbers (but not cardinal arithmetic);

• Asked them to read an introduction to cardinal arithmetic (taken from Stewart & Tall, 1979);

• Recorded their eye-movements as they read;

• Then asked them to complete a comprehension test.

Page 39: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Definitions

Bijection. A bijection, or one-to-one correspondence, is a function f : A ! B which

is both injective and surjective. In other words f is a bijection if (i) for every

a1, a2 2 A, f(a1) = f(a2) =) a1 = a2 (injective); and (ii) if f(A) = B, in other

words if for every b 2 B there exists an a 2 A such that f(a) = b (surjective).

Cartesian Product. Let X and Y be sets. Then the Cartesian Product of X and

Y , denoted X ⇥ Y is the set

X ⇥ Y = {(x, y) | x 2 X, y 2 Y }.

So, for example, R2 = R⇥ R = {(x1, x2) | x1, x2 2 R}.

Cardinal Numbers

‘What is infinity?’. When some first-year university students were asked this question

recently, the consensus was ‘something bigger than any natural number’. In a precise

Basic Definitions

Page 40: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Cardinal Arithmetic

Just as we can add, multiply and take powers of finite cardinal numbers, we can

mimic the set-theoretic procedures involved and define corresponding operations on

infinite cardinals. Some, but not all, of the properties of ordinary arithmetic carry

over to cardinal numbers, and it is most instructive to see which ones. First of all the

definitions:

Addition. Given two cardinal numbers ↵, � (finite or infinite), select disjoint sets

A,B such that |A| = ↵, |B| = �. Define ↵ + � to be the cardinal number of

A [B.

Multiplication. If ↵ = |A|, � = |B|, then ↵� = |A⇥ B|.

Powers. If ↵ = |A|, � = |B|, then ↵

� = |AB| where A

B is the set of all functions

from B to A.

The reader should pause briefly and check that when the sets concerned are finite then

this corresponds to the usual arithmetic. In particular, when |A| = m and |B| = n,

then on defining a function f : B ! A, each element b 2 B has m possible choices of

Defined how to add, multiply and take powers of

cardinal numbers

Page 41: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

uniquely so that

@0 � @0 = ↵ () @0 = @0 + ↵

Because the cartesian product of two countable sets is countable, it is easy to deduce

that

n@0 = @0n = @0 for n 2 N

and @0@0 = @0.

It is interesting to calculate 0@0. This turns out to be zero. In fact we have

0� = 0

for each cardinal number �. This is because A = ; =) A ⇥ B = ; for any other

set B, for if A has no elements then there are no ordered pairs (a, b) for a 2 A and

b 2 B. This means that, in terms of cardinal numbers, zero times infinity is zero, no

matter how big the infinite cardinal is.

ExampleCalculations

Page 42: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

User camera

Tracking cameras

Infrared emittingdiodes

Microphone

Page 43: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Eye-Movements• When viewing static images there are only two

types of eye-movements:

Page 44: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Eye-Movements• When viewing static images there are only two

types of eye-movements:

• Fixations: short (≈200ms) stable period where the eye rests on a single point

Page 45: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Eye-Movements• When viewing static images there are only two

types of eye-movements:

• Fixations: short (≈200ms) stable period where the eye rests on a single point

• Saccades: rapid movements between fixations.

Page 46: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Eye-Movements• When viewing static images there are only two

types of eye-movements:

• Fixations: short (≈200ms) stable period where the eye rests on a single point

• Saccades: rapid movements between fixations.

• Just & Carpenter’s (1980) eye-mind hypothesis: there is a close correlation between eye position and visual attention position.

Page 47: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)
Page 48: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)
Page 49: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Indicative Measures

• Mean Fixation Duration: a measure of processing effort (Just & Carpenter, 1976).

Page 50: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Indicative Measures

• Mean Fixation Duration: a measure of processing effort (Just & Carpenter, 1976).

• Dwell Time (total fixation duration): total attention on a given area (Hauland, 2003).

Page 51: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Indicative Measures

• Mean Fixation Duration: a measure of processing effort (Just & Carpenter, 1976).

• Dwell Time (total fixation duration): total attention on a given area (Hauland, 2003).

• Number of Fixations: more fixations indicates less optimal search (Goldberg & Kotval, 1999).

Page 52: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Indicative Measures

• Mean Fixation Duration: a measure of processing effort (Just & Carpenter, 1976).

• Dwell Time (total fixation duration): total attention on a given area (Hauland, 2003).

• Number of Fixations: more fixations indicates less optimal search (Goldberg & Kotval, 1999).

• Large number of saccades between A and B: may indicate an attempt to find a connection between A and B (Inglis & Alcock, 2012).

Page 53: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Analysis

Questions

1. Did the two groups learn different amounts?

2. Were there between-group differences in aspects of the text which conflicted with existing knowledge?

3. What else differed between the groups?

Page 54: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Preliminaries

• How long did the students spend reading the material?

• Was there between-groups differences in reading times?

Page 55: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Preliminaries

• How long did the students spend reading the material?

• Was there between-groups differences in reading times?

t (17) = 2.327, p = .032

Tota

l Rea

ding

Dura

tion

(minu

tes)

0

5

10

15

20

25

GroupStrong Weak

Page 56: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q1: Learning Differences

Did the two groups learn different amounts?

Page 57: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q1: Learning Differencesr = .570, p = .009

Comp

rehen

sion

Test

Scor

e

0

5

10

15

20

Set Theory Course Grade20 30 40 50 60 70 80 90

Page 58: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q1: Learning Differencest (18) = 3.359, p = .003

Comp

rehen

sion

Test

Scor

e

0

5

10

15

20

GroupStrong Weak

Page 59: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Did the two groups learn different amounts?

Yes, the ‘strong’ group learnt significantly more from the text than the weak group.

Q1: Learning Differences

Page 60: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas• Was this difference due to different ways of

approaching the ‘counterintuitive’ sections of the text?

• The conceptual change account suggests that the weaker students would find these areas more confusing and harder to process than the stronger students.

• Traditional way to measure processing difficulty is by looking at mean fixation duration on a given area (e.g. Just & Carpenter, 1976).

• Longer mean fixations on a given area mean that it was harder to process.

Page 61: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Page 62: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Conflicts with natural number knowledge

Page 63: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Conflicts with natural number knowledge

Page 64: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Conflicts with natural number knowledge

Page 65: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

t (17) = 0.867, p = .398M

ean

Fixa

tion

Dura

tion

(ms)

0

50

100

150

200

250

300

GroupStrong Weak

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Page 66: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

t (17) = 0.867, p = .398M

ean

Fixa

tion

Dura

tion

(ms)

0

50

100

150

200

250

300

GroupStrong Weak

No difference

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Page 67: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

t (17) = 1.078, p = .296M

ean

Fixa

tion

Dura

tion

(ms)

0

50

100

150

200

250

300

GroupStrong Weak

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Page 68: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

t (17) = 1.078, p = .296M

ean

Fixa

tion

Dura

tion

(ms)

0

50

100

150

200

250

300

GroupStrong Weak

No difference

We have g(�) = ✓, as required.

(x) The final equality between cardinals follows from the bjiection h : (A ⇥ B)C !

A

C ⇥ B

C given by writing any � : C ! A⇥ B in terms of

�(c) = (�1(c),�2(c)) for all c 2 C,

then by setting h(�) = (�1,�2). Checking the details is left to the reader. ⇤

Now let’s make some explicit calculations with cardinals. Because a countable union

of countable sets is countable, we find that

n+ @0 = @0 + n = @0, for any finite cardinal n,

and @0 + @0 = @0.

This shows us that we have no possibility of defining subtraction of cardinals where

infinite cardinals are involved, for what would @0 � @0 be? According to the above

results it could be any finite cardinal or @0 itself, so subtraction cannot be defined

Page 69: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas

• No differences between the groups in processing difficulty associated with counterintuitive areas.

• (NB. if you control for individual differences in overall fixation duration, then there are still no differences)

• Also no differences in raw measure of dwell time spent studying these areas, or number of returns to these areas.

Page 70: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q2: Counterintuitive Ideas

Was this difference due to different ways of approaching the ‘counterintuitive’ sections of the text?

No evidence in favour of this hypothesis.

Apparently the two groups found the difficulty of these sections to be roughly similar.

Page 71: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q3: What else?

• If the difficulty was not due to difficulty accommodating counterintuitive knowledge, as predicted by the conceptual change account, why did the weak group learn so much less?

• We looked at where participants focused their attention throughout the text.

• Brief highlights here.

Page 72: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q3: What else?The first question on the comprehension test asked participants to define what it means to say that two sets have the same cardinality.

Q3: What else?

Page 73: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q3: What else?The first question on the comprehension test asked participants to define what it means to say that two sets have the same cardinality.

Q3: What else?

Page 74: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Q3: What else?The first question on the comprehension test asked participants to define what it means to say that two sets have the same cardinality.

Q3: What else?

Page 75: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

sense, this is correct; one of the triumphs of set theory is that the concept of infinity

can be given a clear interpretation. We find not one infinity, but many, a vast hierarchy

of infinities. We can answer a question like ‘How many rational numbers are there?’,

with the surprising reply ‘as many as there are natural numbers’. The most useful

type of question is exemplified by this answer. Rather than ask ‘how many’ elements

there are in a given set, it is much more profitable to compare two sets and ask if

there are as many elements in the two of them. This can be described by saying

that there are ‘the same number of elements’ in sets A and B if there is a bijection

f : A ! B.

Rather than begin with the full hierarchy of infinities, let’s begin with what turns out

to be the smallest of them. The standard set for comparison purposes we’ll take to

be the natural numbers N. It is useful to consider N rather than N0 = {0}[N simply

because a bijection f : N ! B organises the elements of B into a sequence; we can call

f(1) the first element of B using this bijection, f(2) the second, and so on. . . Using

this process we set up a method of counting B. Of course, if we actually say the

elements one after another using this bijection, ‘f(1), f(2), . . .’, we never actually

reach the end, but we do know that given any element b 2 B, then b = f(n) for some

Page 76: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

sense, this is correct; one of the triumphs of set theory is that the concept of infinity

can be given a clear interpretation. We find not one infinity, but many, a vast hierarchy

of infinities. We can answer a question like ‘How many rational numbers are there?’,

with the surprising reply ‘as many as there are natural numbers’. The most useful

type of question is exemplified by this answer. Rather than ask ‘how many’ elements

there are in a given set, it is much more profitable to compare two sets and ask if

there are as many elements in the two of them. This can be described by saying

that there are ‘the same number of elements’ in sets A and B if there is a bijection

f : A ! B.

Rather than begin with the full hierarchy of infinities, let’s begin with what turns out

to be the smallest of them. The standard set for comparison purposes we’ll take to

be the natural numbers N. It is useful to consider N rather than N0 = {0}[N simply

because a bijection f : N ! B organises the elements of B into a sequence; we can call

f(1) the first element of B using this bijection, f(2) the second, and so on. . . Using

this process we set up a method of counting B. Of course, if we actually say the

elements one after another using this bijection, ‘f(1), f(2), . . .’, we never actually

reach the end, but we do know that given any element b 2 B, then b = f(n) for some

Page 77: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)
Page 78: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)
Page 79: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Definitions

• Of course the f(XY) = f(X)f(Y) person wasn’t going to be able to answer this question: they didn’t attend to the definition.

• If they didn’t know what |X| = |Y| meant, the rest of the chapter would have been jibberish.

• Was this lack of focus on definitions the case in general?

Page 80: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Cardinal Arithmetic

Just as we can add, multiply and take powers of finite cardinal numbers, we can

mimic the set-theoretic procedures involved and define corresponding operations on

infinite cardinals. Some, but not all, of the properties of ordinary arithmetic carry

over to cardinal numbers, and it is most instructive to see which ones. First of all the

definitions:

Addition. Given two cardinal numbers ↵, � (finite or infinite), select disjoint sets

A,B such that |A| = ↵, |B| = �. Define ↵ + � to be the cardinal number of

A [B.

Multiplication. If ↵ = |A|, � = |B|, then ↵� = |A⇥ B|.

Powers. If ↵ = |A|, � = |B|, then ↵

� = |AB| where A

B is the set of all functions

from B to A.

The reader should pause briefly and check that when the sets concerned are finite then

this corresponds to the usual arithmetic. In particular, when |A| = m and |B| = n,

then on defining a function f : B ! A, each element b 2 B has m possible choices of

Page 81: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Cardinal Arithmetic

Just as we can add, multiply and take powers of finite cardinal numbers, we can

mimic the set-theoretic procedures involved and define corresponding operations on

infinite cardinals. Some, but not all, of the properties of ordinary arithmetic carry

over to cardinal numbers, and it is most instructive to see which ones. First of all the

definitions:

Addition. Given two cardinal numbers ↵, � (finite or infinite), select disjoint sets

A,B such that |A| = ↵, |B| = �. Define ↵ + � to be the cardinal number of

A [B.

Multiplication. If ↵ = |A|, � = |B|, then ↵� = |A⇥ B|.

Powers. If ↵ = |A|, � = |B|, then ↵

� = |AB| where A

B is the set of all functions

from B to A.

The reader should pause briefly and check that when the sets concerned are finite then

this corresponds to the usual arithmetic. In particular, when |A| = m and |B| = n,

then on defining a function f : B ! A, each element b 2 B has m possible choices of

Page 82: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

WeakStrong

Read

ing D

urat

ion (%

)

0

0.5

1.0

1.5

2.0

2.5

De!nitionAddition Multiplication Powers

Page 83: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

WeakStrong

Read

ing D

urat

ion (%

)

0

0.5

1.0

1.5

2.0

2.5

De!nitionAddition Multiplication Powers

Effect of Group: F(1,18) = 4.956, p = .039

Page 84: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

So if they were not focusing on definitions, what were they focusing on?

Page 85: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

WeakStrong

Read

ing D

urat

ion (%

)

0

10

20

30

40

De!nitionExplanations Proofs Discussion Examples

So if they were not focusing on definitions, what were they focusing on?

Page 86: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

WeakStrong

Read

ing D

urat

ion (%

)

0

10

20

30

40

De!nitionExplanations Proofs Discussion Examples

So if they were not focusing on definitions, what were they focusing on?

Page 87: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

WeakStrong

Read

ing D

urat

ion (%

)

0

10

20

30

40

De!nitionExplanations Proofs Discussion Examples

So if they were not focusing on definitions, what were they focusing on?

Page 88: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

WeakStrong

Read

ing D

urat

ion (%

)

0

10

20

30

40

De!nitionExplanations Proofs Discussion Examples

So if they were not focusing on definitions, what were they focusing on?

Page 89: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

So if they were not focusing on definitions, what were they focusing on?

WeakStrong

Read

ing D

urat

ion (%

)

0

10

20

30

40

De!nitionExplanations Proofs Discussion Examples

t(18) = 4.660,p < .001

NSNS

NS

Page 90: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Summary

• The difference between strong and weak students was not related to how they dealt with their conflicts with existing knowledge;

Page 91: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 1: Summary

• The difference between strong and weak students was not related to how they dealt with their conflicts with existing knowledge;

• The weak students had extremely questionable study strategies:

• They spent around half as long as the strong students reading definitions;

• and 50% longer reading examples.

Page 92: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 2: Improvement?

• If students have ineffective reading strategies, is there a way of improving them?

• Can we simply tell them that they should read more effectively?

• We tried the Self-Explanation Training method.

Page 93: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation EffectChi et al. (1989) asked students to read material on Newtonian mechanics. Those who did well on problems produced more self-explanations: more interpretations of what was read that involved information and relationships beyond those in text.

Page 94: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation EffectChi et al. (1989) asked students to read material on Newtonian mechanics. Those who did well on problems produced more self-explanations: more interpretations of what was read that involved information and relationships beyond those in text.

Chi et al. (1994) trained students to self-explain then had them read a text on the circulatory system. Those with the training learned significantly more than those asked to read the text twice.

Page 95: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation EffectChi et al. (1989) asked students to read material on Newtonian mechanics. Those who did well on problems produced more self-explanations: more interpretations of what was read that involved information and relationships beyond those in text.

Chi et al. (1994) trained students to self-explain then had them read a text on the circulatory system. Those with the training learned significantly more than those asked to read the text twice.

Ainsworth & Burcham (2007) distinguished explanations of different quality. Comprehension of a biology text was related to the types of explanation produced.

Page 96: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation TrainingOur self-explanation training we used was based on that by Bielaczyc et al. (1995) and Ainsworth & Burcham (2007). We used on-screen slides that:

Page 97: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation TrainingOur self-explanation training we used was based on that by Bielaczyc et al. (1995) and Ainsworth & Burcham (2007). We used on-screen slides that:

• Explain benefits of self-explanation;

Page 98: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation TrainingOur self-explanation training we used was based on that by Bielaczyc et al. (1995) and Ainsworth & Burcham (2007). We used on-screen slides that:

• Explain benefits of self-explanation;

• Discuss identifying key ideas, explaining each line in terms of previous ideas or previous knowledge (definitions);

Page 99: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation TrainingOur self-explanation training we used was based on that by Bielaczyc et al. (1995) and Ainsworth & Burcham (2007). We used on-screen slides that:

• Explain benefits of self-explanation;

• Discuss identifying key ideas, explaining each line in terms of previous ideas or previous knowledge (definitions);

• Demonstrate with an example proof;

Page 100: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation TrainingOur self-explanation training we used was based on that by Bielaczyc et al. (1995) and Ainsworth & Burcham (2007). We used on-screen slides that:

• Explain benefits of self-explanation;

• Discuss identifying key ideas, explaining each line in terms of previous ideas or previous knowledge (definitions);

• Demonstrate with an example proof;

• Distinguish self-explanation from monitoring and paraphrasing;

Page 101: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Self-Explanation TrainingOur self-explanation training we used was based on that by Bielaczyc et al. (1995) and Ainsworth & Burcham (2007). We used on-screen slides that:

• Explain benefits of self-explanation;

• Discuss identifying key ideas, explaining each line in terms of previous ideas or previous knowledge (definitions);

• Demonstrate with an example proof;

• Distinguish self-explanation from monitoring and paraphrasing;

• Provide practice reading attempt.

Page 102: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

MethodParticipants:

• 76 undergraduates (26 first year, 26 second, 24 final).

• Self-explanation and control groups (38 each).

Page 103: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

MethodParticipants:

• 76 undergraduates (26 first year, 26 second, 24 final).

• Self-explanation and control groups (38 each).

Proof comprehension test:

• Proof that there exist infinitely many triadic primes.

• Comprehension test based on Mejia-Ramos et al.’s (2012) framework.

• Question order randomised; Total possible score 28.

Page 104: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Design

Control Activity(History Reading)

Randomization into Groups

Self-Explanation Training

Read Proof A

Comp Test A

Self-Expl Group

Control Group

Explain Proof Line-by-Line Using Self-

Expl Training

Explain Proof Line-by-Line

Page 105: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation TypesExplanations:

• Principle-based: explanation based upon definitions, theorems or ideas not explicit in proof.

• Goal-driven: explanation of how structure relates to goal of text (e.g. proving the theorem).

• Noticing coherence: “this is because in line 5 we introduced...”.

Page 106: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation TypesExplanations:

• Principle-based: explanation based upon definitions, theorems or ideas not explicit in proof.

• Goal-driven: explanation of how structure relates to goal of text (e.g. proving the theorem).

• Noticing coherence: “this is because in line 5 we introduced...”.

Non-explanations:

• False: incorrect or no explanation.

• Paraphrasing: repeat in similar or same words.

• Negative monitoring: “I don’t understand this”.

• Positive monitoring: “this makes sense”.

Page 107: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation TypesExplanations:

• Principle-based: explanation based upon definitions, theorems or ideas not explicit in proof.

• Goal-driven: explanation of how structure relates to goal of text (e.g. proving the theorem).

• Noticing coherence: “this is because in line 5 we introduced...”.

Non-explanations:

• False: incorrect or no explanation.

• Paraphrasing: repeat in similar or same words.

• Negative monitoring: “I don’t understand this”.

• Positive monitoring: “this makes sense”.

This is where the students had problems with the cardinality text

Page 108: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation quality

0 1 2 3 4 5 6 7

Self-Expl TrainingControl

* p < .006

*Positive Monitoring

*Negative Monitoring

Paraphrasing

False

No Comment

*Goal Driven

*Noticing Coherence

*Principle Based

Number of Instances0 1 2 3 4 5 6 7

Page 109: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation quality

0 1 2 3 4 5 6 7

Self-Expl TrainingControl

* p < .006

*Positive Monitoring

*Negative Monitoring

Paraphrasing

False

No Comment

*Goal Driven

*Noticing Coherence

*Principle Based

Number of Instances0 1 2 3 4 5 6 7

Page 110: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation quality

Approximately twice as many explanations; twice as many principle-based explanations

0 1 2 3 4 5 6 7

Self-Expl TrainingControl

* p < .006

*Positive Monitoring

*Negative Monitoring

Paraphrasing

False

No Comment

*Goal Driven

*Noticing Coherence

*Principle Based

Number of Instances0 1 2 3 4 5 6 7

Page 111: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Explanation quality

Approximately twice as many explanations; twice as many principle-based explanations

Fewer positive and negative monitoring statements

0 1 2 3 4 5 6 7

Self-Expl TrainingControl

* p < .006

*Positive Monitoring

*Negative Monitoring

Paraphrasing

False

No Comment

*Goal Driven

*Noticing Coherence

*Principle Based

Number of Instances0 1 2 3 4 5 6 7

Page 112: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Comprehension Score

0

5

10

15

20

25Self-Expl GroupControl Group

Scor

e on

Pro

of C

ompr

ehen

sion

Tes

t (0-

28)

GroupYear 1 Year 2 Year 3

Page 113: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Comprehension Score

0

5

10

15

20

25Self-Expl GroupControl Group

Scor

e on

Pro

of C

ompr

ehen

sion

Tes

t (0-

28)

GroupYear 1 Year 2 Year 3

Main effect of condition:F(1,76) = 13.315, p < .001

Page 114: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

ComprehensionANCOVA:

• Between-subjects factor (condition: self-explanation, control).

• Time included as a covariate.

Page 115: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

ComprehensionANCOVA:

• Between-subjects factor (condition: self-explanation, control).

• Time included as a covariate.

Significant effect of condition:F (1, 76) = 13.315, p < .001, �2p = .154

Page 116: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

ComprehensionANCOVA:

• Between-subjects factor (condition: self-explanation, control).

• Time included as a covariate.

Significant effect of condition:F (1, 76) = 13.315, p < .001, �2p = .154

Average scores:

• Self-explanation group: 18.2 (SD=4.2)

• Control group: 14.2 (SD=4.0)

Effect size: very large, d=0.950.

Page 117: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 3: Genuine Pedagogy?

Does this technique work in genuine pedagogical settings?

Page 118: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

MethodParticipants:

• 107 first-year undergraduates; Calculus lectures.

• Self-explanation group (53) and control group (54).

Page 119: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

MethodParticipants:

• 107 first-year undergraduates; Calculus lectures.

• Self-explanation group (53) and control group (54).

Design:

Randomization into Groups

Self-Explanation Training

Control Activity (Study Habits)

Read Proof B

Comp Test B

Read Proof A

Comp Test A'

20 Days Later

Self-Explanation Training

Control Activity (Study Habits) Self-Expl Group

Control Group

Self-Expl Group

Control Group

Page 120: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Proof comprehensionMeasure: proof comprehension scores (out of 10).

Page 121: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Proof comprehensionMeasure: proof comprehension scores (out of 10).Significant effect of condition (p = .016)

Page 122: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Proof comprehensionMeasure: proof comprehension scores (out of 10).Significant effect of condition (p = .016)No significant effect of time; no significant interaction

Page 123: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Proof comprehensionMeasure: proof comprehension scores (out of 10).Significant effect of condition (p = .016)No significant effect of time; no significant interaction

d = .410d = .350

Page 124: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Study 3: Summary

• Promising indications that self-explanation training may provide a solution to the problem of inefficient reading strategies.

• Needs testing with other types of mathematical texts (i.e. content unrelated to infinity, textbook explanations rather than just proofs).

Page 125: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Overall Summary• Students find cardinality a difficult topic to

engage with (very poor performance on our comprehension test);

Page 126: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Overall Summary• Students find cardinality a difficult topic to

engage with (very poor performance on our comprehension test);

• We found no evidence that this was related to conflicts with intuitions of numbers;

Page 127: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Overall Summary• Students find cardinality a difficult topic to

engage with (very poor performance on our comprehension test);

• We found no evidence that this was related to conflicts with intuitions of numbers;

• Rather, problem was considerably more fundamental: students have highly inefficient study strategies which prevents them from engaging with these new mathematical ideas;

Page 128: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Overall Summary• Students find cardinality a difficult topic to

engage with (very poor performance on our comprehension test);

• We found no evidence that this was related to conflicts with intuitions of numbers;

• Rather, problem was considerably more fundamental: students have highly inefficient study strategies which prevents them from engaging with these new mathematical ideas;

• Self-explanation training seems a promising approach.

Page 129: Reading About Cardinality - uni- · PDF fileReading About Cardinality ... Wim Van Dooren a, ... 2004; Vamvakoussi, Christou, Mertens, & Van Dooren, 2011; Vamvakoussi & Vosniadou, 2004)

Thank you

Collaborators:

Lara AlcockChristian Greiffenhagen Mark Hodds

Funder:

[email protected]

homepages.lboro.ac.uk/~mamji