Using Online Homework in Physical Chemistry Courses

C. M. Woodbridge

This paper was completed and submitted in partial fulfillment of the Master Teacher Program, a 2-year faculty

professional development program conducted by the Center for Teaching Excellence, United States Military Academy, West Point, NY, 2009.

Introduction

Physical Chemistry. Those two words strike, if not terror, than at least knee-knocking fear into

the hearts of most undergraduate chemistry majors. To say that Physical Chemistry is not a

popular course is a gross understatement. Although, PChem it is not the capstone course in a

chemistry major, it is reasonably close. This course requires intimate knowledge of a significant

amount of material: Calculus, Physics, General Chemistry, Organic Chemistry, and Analytical

Chemistry. This is probably the first course in the chemistry major that requires the synthesis of

knowledge from a wide range of topics.

Most undergraduate physical chemistry courses are a one-year survey involving four

primary topics: Thermodynamics, Kinetics, Quantum Mechanics, and Statistical Mechanics.

While these are all rather ambitious subjects on their own, many concepts in PChem involve

expanding on ideas learned in introductory chemistry. For example, in General Chemistry,

students are usually required to memorize or recognize the equation used to calculate the

enthalpy of reaction under standard conditions:

><∆−∆=∆ ∑∑ 1tstanreac

oifi

products

oifi

orxn HnHnH

Comment [C1]:

2

When they get to PChem, we explain where the equation comes from (and frequently derive it

from first principles, e.g., dH = dU + PdV + VdP for a system which only undergoes PV work1)

with the idea that students will no longer have to simply memorize this equation. Why then,

does PChem inspire such terror into the heart of undergraduate and graduate students alike?

There have been more studies about factors which influence student success in General

Chemistry courses.2-4 Some factors which have been studied previously are math ability ,

background in chemistry, and, surprisingly, student attitudes. These studies5 “demonstrate that

performance in general chemistry improves with increased formal reasoning and processing,

better mathematics skills, more previous chemistry courses, better self-rating and attitudes about

the course, and higher scores on placement exams.” Factors contributing to student difficulties

in general chemistry3 (as identified by the instruction staff) are presented in Figure 1. Since, in

my opinion, PChem is an expansion on topics students encountered previously in general

chemistry, I would expect that similar factors would influence success in a physical chemistry

course. The only exception in Figure 1 would be “cultural shock” since, presumably, junior-

level students are no longer new to the university system.

Although there are relatively few students about factors influencing success in a physical

chemistry courses, these few studies find a correlation between success and mathematical

background.2, 6-9 One study9 has presented perceptions of students and faculty on what causes

learning difficulties. These perceptions are shown in Figure 2 (student perceptions) and Figure 3

(faculty perceptions). There seems to be good overlap between the concerns of both faculty and

students.

Overall, I agree with the many of the students’ views shown in Figure 2. Although

PChem was a course I looked forward to in college, based on my undergraduate experience, the

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course was based heavily on deriving equations with no accompanying discussion about the

concepts and we used handouts our instructor wrote so we didn’t have a text. I made few

connections between the course material and everyday life and if there were connections

between the lecture and the labs, I frequently missed them. As an instructor (TA or professor), I

made a conscious effort to try and avoid perpetuating these negative experiences in my courses.

4

Learning Difficulties

Course

Cohort Number

Content Overload

Difficult Concepts

Fragmentation

Staff

Power relationships

Students

Cultural shock

General Ability

Motivation

Preparation

Prior experience

Lab

Math

Vocabulary

Prior learning

Conceptions

Methods

Study Skills

Figure 1: Perceptions of student difficulties in general chemistry by the instruction staff. Adapted from Ref. 3.

5

Learning Difficulties

Course

Abstract concepts (52%)

Course is cumulative (19%)

Course is too mathematical (33%)

Inconsistency in exams/lecture/lab

(37%)

Lack of everyday applicability (26%)

Lack of resources (22%)

No deep understanding

(37%)

Overload of course content (41%)

Staff

Inadequate examples in

lectures (26%)

Inadequately prepared lectures

(26%)

No teaching strategy (11%)

Teacher-centered instruction (44%)

Student

Concern re: concept usability

(11%)

No motivation and interest (37%)

Uncertainty about concepts (15%)

Figure 2: Students’ perceptions of their difficulties in PChem. Percentages reported come from students’ responses on survey questions. Adapted from Ref. 9.

I also agree with the majority of the issues identified by the faculty presented in Figure

3.9 One of the most frustrating obstacles to overcome is the lack of student motivation. Since

PChem is not usually anyone’s favorite class, motivational issues are significant. Motivational

issues are complicated by the broad range of abilities of the students in a class. For example, I

had a class of 7 students at Hillsdale College. The “bottom” of my class was a group of two

students who scored B/B- marks on the examinations. In this class, there were some real

superstars. It was very hard for these students to be earning Bs while the rest of their classmates

6

were earning As and they felt dumb. Designing examinations and problem sets that would

challenge the top of the class without making the “bottom” of the class feel dumb or overlooked

was a real challenge.

Learning Difficulties

Course

Abstract concepts

Exams promote memorization

Lack of resources

No tutorials or tutors

Overcrowded classes

Overload of course content

Teacher-centered teaching

Staff

Lack of professional development

Lack of time and support

Overload of teaching work

Too many different things to do

Student

Differences in background

Lack of motivation

Overlooked students

Socio-economic conditions

Successful students inhibit motivation

Tricks rather than understanding

Figure 3: Faculty perceptions of student difficulties in PChem. Adapted from Ref. 9.

Both students and faculty mention the lack of resources available. While there are many

PChem books to choose from, there are relatively few lab manuals (two I know of and a third

that is out of print). Very few books come with a “course packet” that can be loaded in course

management software like Blackboard but most come with an accompanying solutions manual

for students and instructors. Many institutions use Atkins’ text and this comes with the most

supporting resources: solutions manual (instructor and student versions), an e-book, copies of the

7

figures/tables in the text for instructors to use in lectures, and the ARIS homework system

contains questions from Atkins. If you choose another book (e.g., McQuarrie and Simon), all the

figures from the text are available from the publisher to be downloaded. This is in stark contrast

to the volumes of resources available for a General Chemistry text. For example, Silberberg

(published by McGraw Hill) comes with a test bank, a package that can be uploaded to

Blackboard, a student study guide, a student solutions manual, an instructor’s solutions manual,

online homework, CDs containing animations, pre-made PowerPoint slides, downloadable

figures and tables from the text, and the list just goes on. Can students and instructors manage

without all these resources? Certainly. However, it would be nice to have some additional

resources (besides another physical chemistry book) to direct students to when they need help.

Students also look for tricks to solve problems and tricks to aid in memorization of

material rather than looking for a deep understanding of the material. Memorization and tricks

may have worked in previous chemistry courses and they may have even gotten reasonable

grades using these methods, but in PChem these methods typically stop working. Students need

to have a strong understanding of the concepts as well as be able to solve problems; since there

are many equations presented in a given chapter of a physical chemistry textbook, the student has

to determine which one is the correct equation to use in a particular situation. Without an

understanding of the underlying concepts, students are going to consistently make silly mistakes

like trying to apply the ideal gas law to a system in which one is asked to calculate the

temperature of ice. In other words, students have to not only know the equation but also the

restrictions that come along with the equation; without this additional knowledge, all the tricks in

the world aren’t going to help students.

8

Homework that incorporates both conceptual problems and mathematical problems is, I

think, one of the best predictors for success in the course. “Success” may be measured in terms

of a score on a graded event or student satisfaction that they are “getting it.” Additionally , I have

been using Blackboard to do online homework assignments in CH480, Physical Chemistry for

Life Sciences. I chose this method over more traditional pencil and paper methods since students

are able to get instant feedback on their work. Granted, the feedback is limited to whether or not

the answer is correct, but this is more feedback than traditional pencil-and-paper homework sets

get since I allow students an unlimited number of attempts on their homework. This is the third

time I have used Blackboard in this manner – previously, I used this method in a similar course

offered during the summer at the University of Nebraska-Lincoln. Subsequent sections of this

paper will describe the assessment methods used to determine whether online homework was

beneficial in PChem as well as the results obtained for CH480 during the fall of 2008.

9

Assessment Methods

The methods described below were used to assess student performance in CH480 and the success

of using online homework assignments. The students’ background in general chemistry was

considered. There are three possible tracks: 101/102 (regular); 151/152 (advanced); or

validation. Which track a student took was compared to the students’ course grade in order to

assess whether this had an impact on their performance in CH 480.

Students’ performance on graded events were ranked as “Excellent” (> 76%),

“Satisfactory” (64-75%), or “Poor” (<64%). Graded events evaluated in this manner included

the pre-lesson HW, WPRs, and the TEE. Pre-lesson HW was based largely on students’

knowledge of fundamental concepts from pre-requisite courses. A small percentage of the work

(30%) was based on more sophisticated concepts outlined in the reading. WPRs and TEEs

contained questions drawn from fundamental concepts as well as 480-level applications of this

knowledge.

In-class work was also evaluated using periodic one-minute papers10 and lingering

questions papers (aka “muddiest point".9 Each lesson had an “earn back” opportunity where

students wrote a one-minute paper, lingering question paper, or took a short quiz covering

concepts I felt they hadn’t yet mastered. Student work was ranked as “Excellent,”

“Satisfactory,” or “Poor” in each case. Rankings for quizzes were based on the percentages

given in the preceding paragraph while rankings for the papers were based on the following:

Excellent = good question or good summary of the main point at the CH480 level; Satisfactory =

good question or good summary of the main point at the CH101-102 level; Poor = question or

summary indicates they missed the point of the lesson entirely.

10

Blackboard provides a wealth of statistics as well: the number of attempts a student used

to complete an assignment, what time they began an assignment, and all their responses. While

Blackboard doesn’t retain information about how long a student worked on an assignment, it is

easy to get a “flavor” of this by comparing start times.

11

Results

In the fall of 2008, 30 firsties were enrolled in CH480, Physical Chemistry for Life Sciences. All

students were life science majors and most planned to either go to medical school or hoped to

branch Medical Service Corps. In this class, 18 students took CH101-102, 6 took CH151-152,

and 6 validated the general chemistry sequence. The grade distribution for each of the different

tracks is presented in Table 1 below. None of the students who validated or took advanced

general chemistry received a mark below a B, which suggests that students' backgrounds do have

an impact on their success in physical chemistry.

Table 1: Number of students receiving nominally an A, B, or a C in CH480 sorted by the general chemistry sequence they took.

A B C CH101-102

4 10 4

CH151-152

4 2 0

Validation

4 2 0

When comparing students' scores on homework, WPRs and TEEs, scores which remain

the same or increase from homework to WPR to TEE would suggest students learned the

material or retained what they learned. Homework sets included both calculations and

conceptual questions. Students were allowed to submit each homework set an unlimited number

of times in Blackboard and they were given some (albeit minimal) feedback which included

whether their answers were correct and some generic hints on approaching a correct answer.

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Table 2: Comparison of course averages from homework to WPR to TEE. The events are color-coded as follows: green = > 76%; yellow = 64-75%; red = < 64%.. The average for WPRs

includes only those students who took all four WPRs. Homework WPRs Tee MC TEE Calc TEE Thermodynamics

84.80% 71.83% 64.67% 63.40% 64.03%

Kinetics

82.32% 81.43% 58.33% 68.20% 63.27%

Quantum

88.62% 85.41% 57.83% 75.50% 66.67%

Applications

72.30% 64.85% 69.00% 66.93%

TOTAL

86.29% 65.54% 75.40% 71.65% 79.81%

Based on the data shown in Table 2, instead of scores increasing or remaining nearly unchanged

as time went on, scores went down. The drops were not insignificant either; for example,

averages dropped at least 10% from the homework to the WPR to the TEE in, for example,

Thermodynamics. This trend, in my opinion, has more to do with the available resources for

each graded exercise than students' knowledge actually decreasing over time. On homework,

students are allowed to consult their books, their notes, their classmates, online resources posted

in Blackboard, and me. In principle, they have an unlimited amount of time to complete each

homework set as well. On WPRs and the TEE, however, the students are under time pressure

and are only allowed to use a single, double-sided exam data sheet. This type of trend is also

seen in other PChem classes, as shown in Table 3.

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Table 3 Comparison between physical chemistry courses taught at Hillsdale College, University of Nebraska-Lincoln, and USMA.

# semesters Avg. #

students # HW sets HW Avg. Course

Avg. Hillsdale 10 8.2 13.1 86.1 89.7

UNL 10 29.6 12.4 84.7 79.6

USMA 1 30 40 86.2 84.9

Average 85.7 + 0.8 85 + 5

Data presented in Table 3 from Hillsdale College comprises 5 years of a 2-semester Physical

Chemistry sequence taken only by Chemistry majors; the course includes a lab component. Data

from UNL comprises 4 semesters of the first semester of a year-long Physical Chemistry

sequence taken by Chemistry, Biochemistry, and Chemical Engineering majors with no lab

component as well as 6 semesters of a one-semester Physical chemistry course geared towards

Biochemistry majors. Neither UNL course has an accompanying lab. The one-semester course

focuses primarily on Thermodynamics and Kinetics; a small unit (2 lessons) on spectroscopy

was included. Courses taught at UNL and Hillsdale were conducted in a traditional lecture

format. Interestingly, only the Hillsdale courses show an increase going from the homework to

the WPR to the final grade. These students did paper and pencil homework sets and had one

problem set per chapter. They did far fewer problems than either online course, which seems to

suggest that dong more problems and including conceptual problems does not seem to improve

retention of the material.

In addition to comparing course averages on various graded events, student performance

on individual topics was tracked. Three problems on the TEE came almost verbatim from

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previous WPRs. Student performance on these problems was compared between similar

problems on HW and WPRs. The results are presented in Table 4.

Table 4: Percentage of students who earned at least 90% of the points on a graded event for the topic indicated. Percentages correspond to students attempting the problem and not the class as a

whole. HW WPR TEE % on TEE pH of adenosine

0 17 17 63.40

Analysis of mechanism

93 13 9 68.20

Particle in a box

79 40 24 66.60

The thermodynamics question, pH of adenosine, improved dramatically between the homework

and the WPR and students at retained their knowledge about this problem for the TEE. In

contrast, the percentage of students who did well on the quantum mechanics question (particle in

a box) and the kinetics question (analysis of a mechanism) dropped dramatically as time went on.

The kinetics question on the HW has a very high score because of the level of the question asked

was more at the 102 level rather than the 480 level. The decrease in demonstrated knowledge

seems to occur no matter how the data are analyzed.

15

Discussion

The answer to the question about whether online homework improves students' success on

physical chemistry seems to be “no” or “very little” based on the data presented here. Why,

then, do textbook companies continue to spend money to develop and promote online homework

systems ranging from simple test banks which can be added to course management systems like

Blackboard or sophisticated interactive sessions like those in Aris or WebAssign? Just like

athletic practice or practicing musical instruments, students need to drill with chemistry

problems and test their fundamental knowledge. Online homework seems to me to be a

reasonable alternative to the pencil and paper type of homework. The data in Table 5 seems to

support this.

Table 5: Comparison of average homework and course scores in a one-semester Physical Chemistry course.

# semesters Avg. # Students

Avg. # HW sets

HW Avg. Course Avg.

Pencil & paper (UNL) 4 32 9.75 88.5 83.4

Blackboard (UNL) 2 31 22.5 85.6 81.4

Blackboard (USMA) 1 30 40 86.2 84.9

Blackboard Total 3 30.5 31.2 85.9 + 0.4 83.2 + 2

Overall 87 + 1 83 + 2

Students who did pencil and paper homework had a course average which was 6% below their

homework average, which suggests that their exam scores brought their grades down. In

contrast, students who did Blackboard homework had course averages which were 2% lower

than their homework averages so the negative impact of exams on their overall average was

much less. While students’ knowledge of how to solve particle-in-a-box problems seemed to

16

decrease with time in CH480, their course grade didn’t drop very much (~3%) compared to their

homework grade. Homework was only 15% of their overall grade and examinations were 55%

of their overall grade. At the end of the day, it would seem the CH480 students demonstrated

reasonable competence with the material in the course overall.

So why was there no clear trend of improvement from homework to WPR to TEE in

CH480? Homework works if students work homework properly . One study2 shows a

correlation between homework scores and success; anecdotal evidence supports this. There

seem to be three main problems with homework: 1) copying and wargaming in Blackboard; 2)

time management; and 3) student attitudes about PChem. These attitudes prevail whether

homework is assessed online or via pencil and paper assignments. Fundamentally , everything

comes down to time -- students were not convinced that homework is "physical chemistry

practice" just as a daily PT routine is practice for the bi-annual PT tests and therefore students

tried to get the most points for the minimum input of time. The analogy between problem-

solving and athletic practice seems to be particularly apt at USMA and it is an analogy that has

been around for awhile.11

The online homework assignments can be classified into four categories: calculation (C),

mostly calculations (MC), mostly short answer (MSA), and short answer (SA). Calculation

questions were numerical calculations where students had to enter a number. Short answer

questions were either true/false, multiple choice, or fill in the blank. Course averages were

59.4%, 54.1%, 79.3%, and 90.1% for C, MC, MSA, and SA, respectively. Overall, the more

calculations present in the homework, the more the average dropped. I would have expected MC

to have a higher percentage than C, but there were 5-6 students who never did calculations on

these MC assignments but they had to attempt a calculation to get any points on the C type

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assignments. This data fits the "most points for the least time" model very well. Additionally,

there were 5-6 students who would only submit one attempt on a homework assignment and take

whatever score they earned on the assignment whether it was good or bad. There were students

in this group who took this to the extreme of not going back and changing incorrect true/false

answers.

Copying and wargaming (i.e., going through all possible answers on true/false and

multiple choice questions without much thought) are perceived to be time-saving devices. These

behaviors will lead to individual students having high HW scores, lower WPR scores and lower

scores on the TEE. Frankly copying can be a problem whether students do online homework or

paper and pencil homework. While I have no problem with students collaborating with one

another, I do caution them that copying is a poor choice since they will not be able to rely on

their classmates during examination conditions.

Students did comment that they didn’t like Blackboard because they didn’t know why

their answers were wrong. This was problematic for most students as they did not start the

homework assignments until after 5pm the night before it was due; at that time, I was usually

home and unavailable on e-mail or for AI. To be fair, Blackboard is a passive system and

doesn’t understand that the answers 0.003, .003, and 3E-3 are the same so the students have a

good point. I would go back and give them credit for correct answers that Blackboard marked

wrong due to a simple notation issue, I understand why it was hard for them to decide whether

their answer was wrong because of notation or their answer had a more serious problem. To try

and alleviate these issues, I put ranges on numerical answers in order to eliminate rounding

errors and (most) issues with significant figures. I also tried to put cues in the text of the

problem about the type of answer Blackboard was expecting (e.g., use scientific notation, yes/no

18

etc.). I was also very proactive about checking work as it was submitted and contacting students

to let them know that their answer was wrong due to a rounding error or a mathematical error or

a more serious error. Some students felt that was sufficient help but others disagreed. And yet,

there were some students who thought Blackboard was OK (from HW #40 – PChem Top 5 i.e., 5

best things about PChem):

• HW every lesson kinda makes you read the material

• Although I initially was against use of blackboard for homework assignment, I am now a fan of the hw assignments for they prepare you for the WPRs and are a good test of reading material.

• BB homework

And some advice to future CH480 students (from HW #36 – Letter to the future):

• Do the suggested problems for sure along with the assigned homeowrk [sic]…without it, you will be unsuccessful.

• Also, use Blackboard to your advantage – not just for homework credit, but also as a learning aid …. Stay up on the homework even if you do not understand because the problems will come in handy when studying for the big tests.

• The best advice I can give to a p-chem student (under Dr. Woodbridge) is to do the homework assignments completely every night and try to figure out the equations BEFORE going to class. Also, read the discussion boards and the Lesson slides – they help a lot with the homework, often where Tinoco is incomprehensible. Knowing the homework problems sets you up for success on the problem-solving portions of the WPRs.

Despite some students’ dislike of the online homework and some well-thought out

constructive criticisms on their part, I would use it again. The usage statistics are invaluable as

they allow me to determine whether a given assignment was too long or too hard or confusing. I

can tell approximately how long students spend on a given assignment as well as how they are

approaching about the assignment. Prior to the lesson, I can review the assignment summary and

determine which problems they struggled with on and plan for this accordingly, which makes for

a more student-centered lesson. I do think the students who were focused on learning the

material did benefit from doing more problems than they would have done using paper and

19

pencil homework assignments. The students who copied other students or wargamed their way

through the short answer questions are, I think, the same students who would have copied other

students papers or turned in partially complete submissions if we used pencil and paper

homework assignments. It is my opinion that the students looking for shortcuts or to minimize

their time have the wrong attitude about PChem – they are afraid of the course, not interested in

the course, they lack confidence that they can do well in this difficult course, etc. One paper7

notes that faculty expectations and students’ perceptions seem to be at odds; that certainly seems

to be the case here since I think online homework is great and useful while the average student

disagreed.

A search of the keyword “Physical Chemistry” on the Journal of Chemical Education

website returns 1492 articles from the first issue until the April 2009 issue. Of these articles, the

majority are writeups of good lab exercises, good class exercises, or how best to communicate a

difficult concept in PChem. There are explanations of why premedical students should be

required to take physical chemistry and what content is appropriate for them12 as well as course

structure and content.13 Ironically , the course structure described in reference 13 hasn’t changed

much in the last 40 years. There are articles about how faculty should approach PChem so that

students get the most out of the course; these approaches include Keller-type systems.14-16 Most

recently , there has been a great deal of attention drawn to using Mathematica17 to solve/approach

physical chemistry problems and using Process-Oriented Guided Inquiry Workshops.18-19 We

the faculty are still struggling to make PChem palatable to students and yet hold them to a high

standard.

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Conclusions

The use of online homework in CH480 met with mixed success. The students were not

necessarily big fans of online homework but I thought it made the course more student-centered

and provided a wealth of data about how students were approaching the homework.

Performance on graded events decreased going from homework to WPR to the TEE rather than

increasing but yet the drop between total homework averages and the course average is the

smallest in courses like CH480 where online homework is used. Whether this drop can be

attributed to the nature of the graded event (homework is unlimited resources and time with

many different questions vs. examinations have limited resources and time and often only one

type of question on a topic) or student attitudes toward PChem in general is unclear. Students

were satisfied with the course overall. Next year, I do plan to use online homework again. I do

plan to try and address the student concerns with regard to Blackboard as best I can and I plan to

modify the homework so that each homework set contains questions about fundamental concepts

students should have retained form previous courses (~40%), questions about PChem-level

concepts and skills students should acquire from the reading (~20%) and questions from the

previous lesson which will allow them additional practice on key calculations.

21

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2. Hahn, K.E.; Polik, W.F. Factors Influencing Success in Physical Chemistry J. Chem. Ed. 2004 81, 567-572.

3. Kirkwood, V.; Symington, D. Lecturer Perceptions of Student Difficulties in a First-Year Chemistry Course. J. Chem. Ed. 1996 73, 339-343.

4. Carter, C.S.; Brickhouse N.W. What Makes Chemistry Difficult? J. Chem. Ed. 1989 66, 223-225.

5. pg. 567 in Reference 2.

6. Porile, N.T. Diagnostic Quiz to Identify Failing Students in Physical Chemistry. J Chem. Ed. 1976 53, 109-110.

7. Nicoll, G.; Francisco J.S. An Investigation of the Factors Influencing Student Performance in Physical Chemistry. J Chem Ed. 2001 78, 99-102.

8. Derrick. M. E.; Derrick F. W. Predictors of Success in Physical Chemistry. J. Chem. Ed. 2002 79, 1013-1016.

9. Sozbilir, M. What Makes Physical Chemistry Difficult? J. Chem. Ed. 2004 81, 573-578.

10. Angelo, T.A.; Cross, K.P. Classroom Assessment Techniques: A Handbook for College Teachers, 2nd ed.; Jossey-Bass: San Francisco, 1993.

11. Sherrill, M.S. The problem method of teaching physical chemistry. J. Chem. Ed. 1929 6, 260-262

12. Randall, D.L. Premedical Physical Chemistry. J. Chem. Ed. 1932 9, 1096.

13. Amdur, I. Teaching Physical Chemistry at the Massachusetts Institute of Technology. J. Chem. Ed. 1965 42, 191 – 193.

14. Davis, L.P.; Storch, D.M.; Strawser, L.D. Physical Chemistry at USAFA: Personalized Instruction. J. Chem. Ed. 1987 64, 784-787.

15. Bent, H.A. No Easy Way: Experience with a modified-Keller physical chemistry course. J. Chem. Ed. 1974 51, 661- 664.

16. Bent, H.A. You Can’t Win. J. Chem. Ed. 1975 52, 448-450.

17. For example, Zielinski, T.J. Critical Thinking in Chemistry Using Symbolic Mathematics Documents. J. Chem. Ed. 2004 81, 1533-1534.

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18. For example, Hinde R.J.; Kovac, J. Student Active Learning in Physical Chemistry. J. Chem. Ed. 2001 78, 93-99.

19. Process Oriented Guided Inquiry Learning (POGIL) homepage. http://new.pogil.org/ (accessed March, 2009).