a comparison of the chem study curriculum and a conventional approach in teaching high school...

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A Comparison of the CHEM Study Curriculum and a Conventional Approach in Teaching High School Chemistry Robert G. Rainey Minneapolis Public Schools, Minneapolis, Minnesota PURPOSE OP THE STUDY The CHEM Study1 text and accompanying laboratory manual will be available in hard bound copy for the school year 1963-64. The curriculum was developed as a National Science Foundation project, and has been used on a trial basis by several hundred teachers throughout the United States during the past three years. This paper presents an objective and subjective comparison between CHEM Study (CHEMS) and a conventional method of teaching high-school chemistry. Two groups of high-school seniors were used in this study. One group used the CHEMS materials and method which stressed the development of most topics from laboratory evidence, while the topics in the other group were developed through class recitation- discussion methods with the supplemental use of the laboratory. The results were judged by the performance of the students on two tests; theA.C.S.-N.S.T.A. Cooperative Examination in High School Chemistry (Form 1959), and the Final Test of the CHEM Study materials. These tests were administered at the beginning and end of the course. Each group took both tests. LOCALE The students used were enrolled in four classes of chemistry at South High School, Minneapolis, Minnesota. All students were seniors taking chemistry as an elective subject. In the year of this study, 285 students graduated, with 118 having taken chemistry. South is one of eleven Minneapolis high schools, and draws its students from a cross-section of the city^s population with some students coming from families of high income, but with a majority of students coming from families of middle and low incomes. Typically, about 60% of South graduates, who have taken chemistry, continue their education after high school. EXPERIMENTAL CONDITIONS The CHEM Study Group. Two of the four classes used were taught by the CHEMS method. Students were assigned to classes by normal * Chemical Education Materials Study, Director: J. Arthur Campbell, Harvey Mudd College, Claremont, California. 539

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A Comparison of the CHEM Study Curriculum and aConventional Approach in Teaching

High School Chemistry

Robert G. RaineyMinneapolis Public Schools, Minneapolis, Minnesota

PURPOSE OP THE STUDY

The CHEM Study1 text and accompanying laboratory manual willbe available in hard bound copy for the school year 1963-64. Thecurriculum was developed as a National Science Foundation project,and has been used on a trial basis by several hundred teachersthroughout the United States during the past three years. This paperpresents an objective and subjective comparison between CHEMStudy (CHEMS) and a conventional method of teaching high-schoolchemistry.Two groups of high-school seniors were used in this study. One

group used the CHEMS materials and method which stressed thedevelopment of most topics from laboratory evidence, while thetopics in the other group were developed through class recitation-discussion methods with the supplemental use of the laboratory.The results were judged by the performance of the students on two

tests; theA.C.S.-N.S.T.A. Cooperative Examination in High SchoolChemistry (Form 1959), and the Final Test of the CHEM Studymaterials. These tests were administered at the beginning and end ofthe course. Each group took both tests.

LOCALEThe students used were enrolled in four classes of chemistry at

South High School, Minneapolis, Minnesota. All students were seniorstaking chemistry as an elective subject. In the year of this study, 285students graduated, with 118 having taken chemistry.

South is one of eleven Minneapolis high schools, and draws itsstudents from a cross-section of the city^s population with somestudents coming from families of high income, but with a majority ofstudents coming from families of middle and low incomes. Typically,about 60% of South graduates, who have taken chemistry, continuetheir education after high school.

EXPERIMENTAL CONDITIONSThe CHEM Study Group. Two of the four classes used were taught

by the CHEMS method. Students were assigned to classes by normal

* Chemical Education Materials Study, Director: J. Arthur Campbell, Harvey Mudd College, Claremont,California.

539

540 School Science and Mathematics

scheduling methods and a flip of a coin placed a morning and anafternoon class in this group. Approximately one-third of each classwas girls. In all, 56 students studied chemistry using the CHEMStudy materials.The CHEM Study Materials. Part of the philosophy of the CHEMS

program is to establish laboratory evidence in order to deduce theprinciples operating in chemistry. From the first day in class, usingthe familiar lighted candle experiment, the students were asked tosuggest reasons for everything they saw and did. Such topics asenergy of reactions and heat effects were dealt with early in thecourse, while atomic theory and equation balancing appeared late inthe course. The laboratory experiments were of the directed type,rather than the problem-solving or open-end type, although there wassome opportunity for the latter during the second semester. In termsof time, a minimum of three days per week were spent in the labora-tory by this group.The text material developed and expanded the laboratory work

which preceded it. Rather difficult problems at the end of chapterswere used as homework, along with regular reading assignments inthe text.

Eight films were used to supplement the course. Some of the ani-mated parts showing molecular vibrational modes, collision theory,and reaction mechanisms were excellent.2By making the course essentially a laboratory course, the CHEM

Study authors hoped to develop materials applicable to the generalstudent who takes high-school chemistry, rather than to the gifted orupper part of the class. (An observation was that an understanding ofthe theory behind many of the concepts presented in the CHEMSmaterials called for up-to-date training on the part of the teacher.)

The Conventional Group. As in the case of the other group, twoclasses of students, assigned by regular programing procedures, com-prised this group. One class met in the morning, the other in theafternoon, and included 62 students in all. Of the 62 students, 18were girls.

The Conventional Materials. The procedure used with this grouphad one underlying principle; text assignment and class recitation-discussion preceded all laboratory work. All laboratory work was anoutgrowth from class material, and attempted to extend it to newsituations. Eighteen experiments were done by this group during theyear, with ten of these being open-ended in the sense that studentscould go on to other facets of the same general experiment. Typically,it was small groups of students that branched out and went on during

2 A new film has been added to this series that includes the original planning and actual carrying out of theexperiment making KrFa.

A Comparison on Chemistry 541

the laboratory work, but their findings were shared with the wholeclass during the discussion periods following each laboratory assign-ment. No general laboratory manual was used, however the experi-ments were modifications of those found in most commercially pre-pared manuals. Laboratory work was presented in the form of prob-lems to solve, with students working individually and independentlyin the laboratory. The average time spent in the laboratory was twodays per week.A basic text, Modern Chemistry, Dull & Metcaife, was used with

reading assignments and end-of-chapter problems done by the stu-dents. No films were shown to this group.

Elements Common to BothGroups. The numbers of tests and quizzesas well as testing time was kept as constant as possible for bothgroups. However, the CHEMS classes were quizzed on CHEMSmaterial, and the conventional classes were quizzed only on whatthey were studying.

Students of both groups kept laboratory notebooks. A generalformat was used to report laboratory work which consisted of stu-dents stating the problem, procedure, findings, and conclusions in thewriteup.

HYPOTHESES TESTED

Since this study was an attempt to determine the effects of twomethods of instruction on achievement in chemistry as measured bytwo tests, the following null hypotheses were tested.

1. There is no significant difference between the mean test scoresof the two groups at the start of the year on either test.

2. There is no significant difference between the mean test scoresof the two groups at the end of the year on either test.

Sampling Method. Because special scheduling problems such asadvanced mathematics, choir, and other special activities made com-plete randomization of students into classes impossible, a matchedpair technique was used, using Differential Aptitude Test scores inNumerical Ability and Verbal Reasoning as the criteria for matching.Raw scores of students were plotted on a graph using Verbal

Reasoning as one axis, and Numerical Ability as the other. Figure 1shows the results of this plot. Whenever two students from eachgroup were within two points of each other, on either Verbal Reason-ing or Numerical ability, a circle was drawn around their numbers andthey constituted a matched pair. Twenty-five such pairs were ob-tained from the 118 plotted points.

Admittedly, Verbal Reasoning and Numerical Ability are not theonly intelligence factors operating in learning chemistry. Such things

School Science and Mathematics

A Comparison on Chemistry 543

as motivation, family background, socio-economic factors, previoustraining, reading ability, and a host of other things were not takeninto account in matching students. When complete randomization ofstudents into treatment groups can be done, the assumption isgenerally made that all these human factors that cannot be controlledare operating equally over both groups. Since randomization was notpossible in this study, matching of students on two criteria was doneas an alternative. The assumption of the myriad of other factorsoperating equally over both groups cannot be made, and it is un-known what effects these might have had in this study.

Analysis of the Data. The statistical tool used in this analysis wasthe t-test for correlated measures. The form of this test is given as:

D

,/^V N

where

D=^D

~N~and

02�OD �

N^D2 - (SZ))2N(N 1)

and D is the total of the differences between the scores of the matchedpairs.

Table 1 shows the summary of the results of the analysis of eachpre- and post-test. There was no significant difference between thescores of the two groups at the start or at the end of the study. Table1 shows the CHEMS groups slightly higher on the CHEMS test, andthe conventional groups slightly higher on the A.C.S. test at the endof the study, however neither difference was significant at the 5%level.

TABLE 1. PRE- AND POST-TEST COMPARISONS

Test

A.C.S. Pre-TestCHEMS FINAL Pre-TestA.C.S. FINAL-TestCHEMS Final FINAL-Test

Group

Conven-tional

6.13.6

37.6116.8

Means

CHEMS

6.43.1

37.5019.8

*t

.27

.34

.181.10

Decision

Accept HypothesisAccept HypothesisAccept HypothesisAccept Hypothesis

* To be significant, t must be greater than 2.064 (5% level).

544 School Science and Mathematics

Summary and Conclusions. This study was an attempt to comparethe new CHEMS curriculum with that of a more conventional cur-riculum in high school chemistry. The investigator made this com-parison during the first trial use of the CHEMS materials.

Student scores on the Differential Aptitude Test sections ofNumerical Ability and Verbal Reasoning were used as a basis formatching. Analysis of the paired scores on the A.C.S. Form 1959Test, and the CHEMS Final Test, showed no significant differences.On the basis of this evidence, it was concluded that neither approachunder study showed superiority in student learning as measured bythese tests.

Subjective Observations. In addition to the above measurablefactors, several less tangible outcomes were observed by the investi-gator during the course of the study. They included:

1. Students in the conventional classes consistently producedbetter write-ups of experiments than in the CHEMS classes. Theywere neater, more complete, and contained better conclusions. Apossible explanation might be that the students in the CHEMSclasses believed they were merely repeating the detailed directions oftheir laboratory manuals, although the format included their owninterpretation of the data.

2. Students in the CHEMS classes seemed to enjoy their labora-tory work more. On a student reaction sheet given to all classes atthe conclusion of the course, the CHEMS students consistently statedthat the laboratory work was the most enjoyable part of the course,while those in the conventional classes were less consistent with thiskind of comment. Since the CHEMS laboratory manual was wellorganized and proceeded through carefully devised experiments,students were able to anticipate errors, while those in the conven-tional classes using open-end experiments had to learn through mis-takes about quantities of material and types of apparatus to use.Many students in the conventional classes resented this, and statedthat they would rather be told what to do than make mistakes andhave to start over.

3. Students in the CHEMS classes felt more hurried in their labora-tory work because of the more rigid time schedule imposed on them tofinish all the material during the trial year. Students in the conven-tional classes were not under any pressure to finish, and were allowedto explore other things related to a specific assignment in the labora-tory within a reasonable time limit.

4. On the basis of the experience of this investigator, the CHEMScourse offered a reasonable and workable approach to teaching highschool chemistry. The laboratory work did the teaching. If individualwork in the laboratory is impossible, the CHEMS curriculum offersan excellent alternative in paired and group laboratory work.