subtitle: considering the elusiveness and importance of...
TRANSCRIPT
Number Necessities: Number Sense & Fluency
subtitle: considering the elusiveness and importance of number sense - NOW.
Francis (Skip) Fennell
McDaniel College
Westminster, MD
www.mathspecialists.org
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Now – he tweets…
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F. (Skip) Fennell ��@SkipFennell
A sense is number is acquired - it's developed. YOU don't teach number sense, you teach to nurture its development.
Some History!
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Curriculum and Evaluation Standards, 1989
Children with good number sense
1. Have well understood number meanings,
2. Have developed multiple relationships among numbers,
3. Recognize the relative magnitude of numbers,
4. Know the relative effect of operating on numbers, and
5. Develop referents for measures of common objects and situations in their environments.
7NCTM, 1989, page 38; Hilde Howden
Others
• Bob and Barbara Reys
• Jack Hope
• Judy Sowder
• Ed Rathmell and Chuck Thompson
• Bob Siegler
• Paul Trafton - A sense of
number unfolds
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More recently…
• …poor number sense interferes with learning algorithms and number facts and prevents use of strategies to verify if solutions to problems are reasonable.
9NMAP, page 27, March 2008
And for us (adults)
• Number sense is implicated in virtually any quantitative task, from deciding whether a price is reasonable to interpreting statistical information about the risks associated with a medical treatment (Curry, et al., 1996; Steen, 2001).
• Really? Take a look…10
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• University of Missouri researchers recently tested 180 seventh grade students in the Columbia, Missouri school system and found that kids who lacked math fluency in middle school were the same kids who struggled with number concepts in first grade (Geary, 2013).
• Parents can do plenty to help kids gain number sense.
Not just for parents…
• Introduce children to numbers as soon as possible.
• Present math activities with the same enthusiasm that you display for language acquisition and reading.
• Go beyond counting! (5 cookies is the amount five and we use 5 to represent that amount).
• Play math games that informally engage operations.
• Measure – pretty much everything
• Talk about time
• And on and on…
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Do you have a sense of number?
Is 4 x 12 closer to 40 or 50?
How many paper clips can you hold in your hand?
If the restaurant bill was $119.23, how much of a tip should you leave?
How long will it take to make the 50 mile drive to Washington, D.C.?
If a 10-year old is 5’ tall, how tall will the child be at age 20?
Contributors to Number
Sense Development
• Conceptual Understanding
– Counting
• Subitizing
– Place Value; Comparing and Ordering• Composing and decomposing
• Mental Math Opportunities
• Estimation
– Magnitude
– Computational Estimation
• Reasonableness of Results
• Questioning to promote a sense of number…
• Numbers in context22
All students should leave elementary school computationally fluent AND with a
strong sense of number
What does that mean?
Why is that important?
How do we do that?
AND, does the CCSS-M help?
Consider…
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Number Sense
Foundations
Practices
Fluency
from the CCSS-M
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K 1 2 3 4 5
Counting, cardinality,
comparing
Extend the counting
sequence
Understand addition as
putting together and
adding to, and
understand subtraction
as taking apart and
taking from
Understand and apply
properties of operations
and the relationship
between addition and
subtraction
Understand properties
of multiplication and
the relationship
between multiplication
and division
Work with numbers 11-
19 to gain foundation
for place value
Understand place value
Use place value
understanding and
properties of operations
to add and subtract
Understand place
value
Use place value
understanding and
properties of
operations to add and
subtract
Use place value
understanding and
properties of operations
to perform multi-digit
arithmetic
Generalize place value
understanding for
multi-digit numbers
Use place value
understanding and
properties of
operations to perform
multi-digit arithmetic
Understand the place
value system
Perform operations with
multi-digit whole
numbers and with
decimals to hundredths
Develop understanding
of fractions as numbers
Extend understanding
of fraction equivalence
and ordering
Use equivalent fractions
as a strategy to add and
subtract numbers
Apply and extend
previous understandings
of multiplication and
division to multiply and
divide fractions.
15 – why is this number important????
Subitizing
Sun Mon Tues Wed Thur Fri Sat
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31
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100 Chart Puzzles
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24 26
Hmm…think about this
• Comparison time increases as the numbers to be compared become close to the reference number.
• It takes more time to determine that 71 > 65 than 79 > 65, and comparing 69 to 65 takes more time than comparing 71 to 65.
• Just one example of the importance of place value as a mathematical foundation in work with whole numbers. (but what about fractions…more later!)
29Dehaene, The Number Sense, p. 75
• For students in grades K-2, learning to see the relationships between addition and subtraction is one of their most important accomplishments in arithmetic.
Resnick, L.B. (1983)30
Math Wall Activities
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Today’s Date
Composing and Decomposing Number is Critical!
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100
• 100 is a big number when it’s:
• 100 is a small number when it’s:
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Number Sense Language
• bunch
• pile
• flock
• herd
• stack
• handful
• basket
• cord
• crowd
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Favorites
• Write 3 numbers that have some significance to your life.
• Exchange lists. Provide random clues for the numbers.
• Guess which numbers fit the clues.
Computational fluency - having and using efficient and
accurate methods for computing. Fluency might be
manifested in using a combination of mental strategies and
jottings on paper or using an algorithm with paper and pencil,
particularly when the numbers are large, to produce accurate
results quickly. Regardless of the particular method used,
students should be able to explain their method, understand
that many exist, and see the usefulness of methods that are
efficient, accurate, and general. (PSSM, 2000, page 32).
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Procedural fluency refers to knowledge of
procedures, knowledge of when and how to use
them appropriately, and skill in performing them
flexibly, accurately and efficiently (Adding it Up,
2001, page 121).
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…the Panel proposes three clusters of concepts and skills – called the Critical Foundations of Algebra –reflecting their judgment about the most essential mathematics for students to learn thoroughly prior to algebra course work.– Fluency with Whole Numbers – By the end of Grade 5 or 6,
children should have a robust sense of number…
– Fluency with Fractions – Before they begin algebra course work, middle school students should have a thorough understanding of positive as well as negative fractions…(National Mathematics Advisory Panel, pages 17, 18, 2008).
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Fluency: Simply Fast and Accurate? I Think Not!
By NCTM President Linda M. GojakNCTM Summing Up, November 1, 2012
…a frequently asked question is, “What does it mean to be fluent in mathematics?” The answer, more often than not, is, “Fast and accurate.” Building fluency should involve more than speed
and accuracy. It must reach beyond procedures
and computation.
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The fluency thing…
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K 1 2 3 4 5 6
Facts
Fluently add and
subtract within 5
Add and subtract
within 20,
demonstrating
fluency for addition
and subtraction
within 10. Use
strategies…
Fluently add and
subtract within 20
using mental
strategies. By the
end of grade 2, know
from memory all
sums of two one-
digit numbers.
Fluently multiply
and divide within
100, using
strategies…By the
end of Grade 3,
know from memory
all products of two
one-digit numbers.
Operations, Algorithms
Fluently add and
subtract within 100
using strategies
based on place
value, properties of
operations, and/or
the relationship
between addition
and subtraction
Fluently add and
subtract within
1000 using
strategies based on
place value,
properties of
operations, and/or
the relationship
between addition
and subtraction
Fluently add and
subtract multi-digit
whole numbers
using the standard
algorithm.
(capstone)
Fluently multiply
multi-digit whole
numbers using the
standard algorithm.
(capstone)
Fluently divide
multi-digit whole
numbers using the
standard algorithm.
(capstone)
Fluently add,
subtract, multiply,
and divide multi-
digit decimals using
the standard
algorithm for each
operation.
(capstone)
Fractions? What price fluency?
How Does Computational Fluency
Develop?
• Experience along the continuum enables the student to better determine the reasonableness of an answer.
• Students move along the continuum at individual rates.
• Often it is the difficulty of the problem that determines the strategies the student will use.
Carpenter, T., Fennema, E., Franke, M., Levi, L., & Empson, S. (1999). Children’s
Mathematics. Portsmouth, NH: Heinemann
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Computational Fluency, Algorithms, and Mathematical
Proficiency: One Mathematician’s Perspective
Hyman Bass, TCM, February, 2003.
“Understanding algorithms is central to developing computational fluency. Teachers must combine a renewed appreciation of the contributions algorithms make to mathematical proficiency with a design of approaches to teaching and learning that can develop both understanding and skill. They also must appreciate what efficiency affords and respect what it takes to use compact methods sensibly,
flexibly, and appropriately.” 42
Well, of course…
The Practices and Number Sense
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Make sense of problems and
persevere in solving them.
…and they continually ask themselves, “Does this make sense?”
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Reason abstractly and
quantitatively
“…considering the units involved; attending to the meaning of quantities, not just how to
compute them; and knowing and flexibly
using different properties of operations and objects.”
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Construct viable arguments and
critique the reasoning of others
“…Such arguments can make sense and be correct, even though they are not generalized or made formal until later grades…Students
at all grades can listen or read the arguments of others, decide whether they make sense,
and ask useful questions to clarify or improve the arguments.” 46
Model with mathematics
“…routinely interpret their mathematical results in the context of
the situation and reflect on whether the results make sense, possibly improving
the model if it has not served its purpose.”
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Use appropriate tools strategically
“…They detect possible errors by strategically using estimation and other
mathematical knowledge.”
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Attend to precision
“…They calculate accurately and efficiently, express numerical answers with a degree of precision appropriate
for the problem context. In the elementary grades, students give
carefully formulated explanations to each other.” 49
Look for and make use of structure
“Mathematically proficient students look closely to discern a pattern or
structure. …will see 7 x 8 equals the well remembered 7 x 5 + 7 x 3, in preparation for learning about the
distributive property…” 50
Look for and express regularity in
repeated reasoning
“Mathematically proficient students notice if calculations are repeated, and look both for
general methods and for shortcuts. …As they work to solve a problem, mathematically
proficient students maintain oversight of the process, while attending to the details. They continually evaluate the reasonableness of
their intermediate results.” 51
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Boxes to multiply…
• Draw a rectangle to show 46 x 7 = 322
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40 6280
4246 x 7 = (40 x 7) + (6 x 7) =
280 + 42 = 322
The importance of representations…
Blame it on your brain…
• We become so skills focused with the how’s and procedural “stuff” related to computation (mental or paper/pencil) that the “work” starts automatically…
• A farmer has eight cows. All but five die. How many cows remain?
• Judy owns five dolls, which is two fewer than Cathy. How many dolls does Cathy have?
• 3 for each?
54Dehaene, The Number Sense, p. 75
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Estimation – Some Thoughts
• Estimating Magnitude – should begin early and occur often.
• Children are initially uncomfortable with computational estimation.
• The language of computational estimation is adult language. Children seem OK with such language as they grow –experientially.
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Estimate or Exact?
• Your school bus number.
• When to leave for school in the AM.
• When a flight will leave the airport.
• Total bill at a restaurant.
• When do you estimate?
• When must you have an exact response?
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Why Fractions?
• 50% of 8th graders could not order three fractions from least to greatest (NAEP, in NCTM, 2007).
• Less than 30% of 17-year olds correctly represented 0.029 as 29/1000 (Kloosterman, 2010).
• When asked which of two decimals, 0.274 and 0.83 is greater, most 5th and 6th graders chose 0.274 (Rittle-Johnson, Siegler, and Alibali, 2001).
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Also consider…
• Sowder (ed., 1989) noted that “number size is not a sense about numbers that once acquired for whole numbers generalizes to all kinds of numbers” (page 20).
• The National Mathematics Advisory Panel (US Deptof Education, 2008) in its final report noted that: “the most important foundational skill not presently developed (among foundational skills necessary for algebra) appears to be proficiency with fractions (including decimals, percent, and negative fractions).” (NMAP, 2008, page 18).
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Fraction beginnings…
• Which one is larger, 1/2 or 1/3?
“the size of the fractional part is relative to the size of the whole…” (NCTM, 2006)
Got Fraction Sense?
62Video here from hand2mind, 4.30.13
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Fractions are numbers too!
Developing Fraction Sense
• Representations
• Equivalence
• Comparing and Ordering Fractions
• Connections (e.g. between)
• Contexts
65Fennell, Kobett, and Wray, MTMS, April, 2014
66Fennell, Kobett, and Wray, MTMS, April, 2014
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Fennell, Kobett, and Wray, MTMS, April, 2014
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Percent Benchmarks
0%
100% 50% < 10%
~25% ~75% ~90%
> 50% < 50%
• Lefthanders in the room or class
• Once lived in New Jersey
• Been involved in education > 10 years
• People who were born in Maryland (?)
Number Sense, Addenda series
Ready??
Contexts – well maybe…
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What did he say?
117,203 attended the Preakness…• “less than .0025 of the crowd was arrested/detained…”
• Who could have possibly understood this
statement?????
• Why did he do this? I know, and you probably do too!!!!!
• Hmm – 0.0025, what do I do with that? I’ll just read
it.
• How about just saying less than 1% since it’s really ¼ of 1%? OR
• Less than 1%, fewer than 300 of the 117,000+ attendees!
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Really?
• The weather reporter on WCRB (a Boston radio station) said there was a 30% chance of rain. The host of the show asked what that meant.
• The weather reporter said, ``It will rain on 30% of the state.''
• ``What are the chances of getting wet if you are in that 30% of the state?''
• ``100%.'‘
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You can’t make this stuff up
• 50% off sale on all purchases at the Izod store. Sign indicates 50% off the all-store sale.
• Patron – “well that means it’s free.”
• Clerk – “no sir, it’s 50% off the 50% off sale.”
• Patron – “well, 50% + 50% is 100% so that means it should be free.”
• This went on for a while. AND, there was a sign indicating 70% off for some items, meaning 70% off the 50% off original sale, which our patron would interpret as the item being free and 20% in cash!
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What can you do in a minute?
Time as a context…
• Sit-ups
• Listen to a song
• Finish my homework!
• Do a chore
• Wait a minute – really?
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“Oh, about 2:45”
What is your expected finishing time?
Are you sure?
• Actual problem presented at an NCTM regional conference.
• A dog traveled 15 meters per second. How far would the dog go in: a minute, a half-hour, an hour, a day?
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Speeds of Some Animals
Cheetah 70 mph (65)*
Lion 50 mph
Zebra 40 mph
Rabbit 35 mph
“Super Dog” 33+ mph
Reindeer 32 mph
Elephant 25 mph
Chicken 8 mph
Consider…
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Number Sense
Foundations
Practices
Fluency
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It added that the wealth of the richest one percent of people in the world now amounts to $110 trillion, or 65 times the total wealth of the bottom half of the world's population.
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Concluding Thoughts
• Number sense is elusive.
• Understandings provide anchors for developing number sense.
• Number sense should be nurtured – every day! And such opportunities connect to and extend standards (e.g. estimation, mental math - reasonableness)
• A sense of number breeds confidence.
Questions?
http://www.mathspecialists.org
http://www.ffennell.com