Robert C. Grondey Chemical Sciences University of Illinois Urbana, lilinois 61801
schoolof
The Use of Computers to Aid Instruction in Beginning Chemistry
Among the most difficult problems for beginning chemistry studcnt,~arc thosc which require the use of scvcral strps or a combination of concepts. An undcrstanding of cach stcp in the problcm solving procedure usually requires an undcrstanding of cach preceding step. When the procedure is explained in a group situation such as a lecture it is impossible for the instructor to bc surc that cach studcnt is capable of procceding t,o the next stcp. Thus t,here are always a number of st,udents who become lost at varying points in the presentation. The ideal situation would be to provide for each individual student a tutor who would introduce the concepts and procedure of each step in detail, make sure that the student understands cach step before proceeding t,o the next, provide encouragement when t,he student is doing well, detcrmine when thc studcnt is having trouble and provide help, hintas, and needed review, tell t,hc studcnt what is wrong wit,h his answer and in general make surc that the student doesn't reach a point from which it is impossible for him to continue. The abilit,y of thc digital computcr to store data and to be programmed to make decisions makes it a logical tool for achieving true individualized instruction. Computer-aided lessons on determining chemical formulas from composition by weight, quantities from chemical equations, and balancing cquations for oxidation-rcduct,ion reactions have been developed and used on the PLATO system at the University of Illinois. The PLATO system which has been described elsewhere' provides a television screen and a lceyset for each student. The student can easily type a number of special upper and lower case characters including subscripts, superscripts, and arrows for chemical equations in addit,ion to the characters normally found on a typewriter. The display of a chemical equation on the screen looks the same as the student would see it in his text.
individual t.o individual. The student is given a number of opportunitics to request additional information, helps, hints, more practice or review. The computer is also programmed to determine when the student is having trouble and is able to guide t,he student into the proper hclp sequence. Thc sequence determining decisions arc sometimes made on the basis of the results of one question while a t other times the results of a series of questions are considered. Throughout the introductory section of each lesson new steps or concepts are preceded by a review of what is already known. Often the studcnt is guided through the problem step by step to the point whers the new stcp is needed. I n the practice prohlem section of the lesson the student is given the data and askcd for the final answer. Help sequences with step by step guidance and suggestions are available at the student's request. The student is able to terminate the help sequence a t any point and return to t.he problem. The student can use the computcr as a calculator at any time. In the lessons on the determination of chemical formulas and calculat,ion of quantities from chemical equations, the student is able to supply his own problems in addition to choosing problems from a list stored in the computer. Figures 1-3 show how the student would supply the data for the calculation of the number of kilograms of barium sulfate that could he produced by reacting 450 g of barium hydroxide with sulfuric acid. The computer has been programmed to interpret the student's data and to calculate the correct answer. For each problem the computer determines specific suggestions and questions for use in the help sequence.
Description of Lessons
Each lession consists of an introductory section, practice problems, and a dianostic puiz. I n the introduction of each topic the student is involved in the development of the problem solving procedure. Information is presented and the student is asked to draw conclusions or specify what additional inform* tion is needed. Each student is able to work a t his own speed and can go back over the material. Although each student covers the same general material, the sequence and the form of the questions varies from
' ALPERT, D., AND BITZER, D. I,., SMITH,
Scirneo, 167, 1582 (1070). S. G., J. CHICM.Enuc., 47, 608 (1970).
Figure 1. Example of rtudent supplied rtoichiometry problemr. Top: The student hor typed the balanced eqvotion for the readion. The -ok- after the equation indicoter that the computer has accepted this properly written and balanced. as a valid Middle: The student ho. specified the formulo of the compound for which quantitative informotion is known. The computer immediately determined thot Bo(OHI2 wor in the original equation and coicvloted the formulo weight. The rtudent does not supply atomic weights. for which the quantity was to be Bottom: The formulo for the coiculded has been supplied. The computer has accepted this response and has calculated the formulo weight.
Volume 48, Number 12, December 1971
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791
Figure 2. The original equation has been displayed and the student was asked to supply the quontitotive information. Any unit. of mars moy be rpeciflcd.
Figure 3. The computer has dirpioyed the doto and hor orked for the student.. ontwer.
For example, a question in the help sequence for the above problem would be "What is the weight of a mole of Ba(OH)%?." The diagnostic quizzes contain questions about the individual concepts and steps as well as complete problems. I n each case the student is permitted to attempt a question a specified number of times before it is counted wrong as far as scoring is concerned. Immediately after each attempt, the student is told if his answer is correct or incorrect. While in the test mode the only help available is the use of the computer as a calculator and an indication of the direction of errors on numerical problems. Immediately after the quiz the student is shown his score and is given a review of all the areas in which he did poorly. If the student misses a numbcr of questions related to t,hc same principle, a review of the introductory mat,erial concerning that principle is employed. If the studcnt misses only a few isolated qucstions, he is given another try a t thosc qucst,ions. When in the review mode, hclp is available. Additional problems similar to those missed may also be prcsent,ed. To act as an effective tutor the computer must be programmed not merely to dctcrminc if a student's answcr is corrcct or incorrrct but to dctcrminc precisely what, if anything, is mrong with it: If the student is to learn from his crrors it is important that hc be told why his answer is unacceptable. This information can also be used by the computer to make sequence determining decisions. Throughout the development of these lessons, considerable importance was placcd on routines which would provide a large amount of feedback to the student without placing artificial restraints on the form of the student's answer. Essential features of thcsc 792
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Journal o f Chemical Education
routines arc that they accept all forms of t,hc corrcct answer, pcrmit the lcssoo author to spccify t,hc corrcct answer easily, providc fccdback which is rclcvant,, and pcrform their function in lrss than one sccond. Many questions in chemistry lessons require labclcd numerical answers. For cxamplc, 117 g is a corrcct response to the qucstion "What is the wcight of two moles of sodium chloride?." However, there are a number of rcsponscs which would also be corrcct. A few examples arc: 1.17 X 10%g, 117 g of NaCI, 117 g of sodium chloride, 1.17 X lo2 grams, and 117 gs. It would be impractical and probably impossible for a lesson author to list, all of the aocept,able answers, cspccially if a numerical tolcrance was permitted. Thc task would become even morc staggering if the author had to list all of the anticipated incorrect answers. A special routine was dcsigncd specifically for this situation. The lesson author simply indicates the required units, if any, and the numerical value of t,he correct answer and the tolerance (or directs t,hc computer to calculate these values). He may also list additional required, permitted, or prohibited words. The student is told if his answer is improperly labeled, and if his answer is too high, too low or if the decimal is in the wrong place. The lesson author can also provide feedback for specific errors. For example, he easily can indicate t,hat if a student types 55.5 g, he should be told "No, that is the weight of one mole of sodium chloride." Table 1 contains some examples of the computer's interpretation of some typical student responses. Table I .
Examples of Student's Labeled Numerical Answers and the Computer's Response --
--
-
Correct answer 623 i 2 g Student's answer Computer's response
Please label your answer
-
ok 6.24 X 10Zg 628 g. 621 grams 6.24 X lo8 g
ak Your answer is too high Your answer is too low Your answer is too high, decimal error
Answers in the form of chemical formulas and equations must be intcrpreted in s different way than a normal sentence. For example, if a student types NHzOH for the formula of ammonium hydroxide he should be told that the hydrogen is incorrect and not that he has misspcllcd a word. The routine which was developed to interpret chemical formulas detects improper symbols of the elements, improper use of parent,heses and subscripts, and also determines which elements are not correct. The routine which interprets chemical equations cheeks each formula for the above err,ors and also det,ermines if the equation is balanced by both charge and mass. This routine also permits the lesson author to specify which species are required or prohibited in the cquattion. He can also specify whether the species must be reactants or products. When the student types his answer, the computer checks for errors and determines within one second whcthcr the rcsponse is acccptablc or unacceptable. Figure 4 shows the computer's ioterprctation of a student's attempt to balance the equation for the oxidation of iodide ions by dichromate ions.
Table 2. Comporison of Course Grader Spring, 1970" -
~~~
E PLAT0 instruotion
(nom!>ei) (peroent)
4 22
PLAT0 review only (number)
0 0
-
Analysis of Effectiveness
I n the Fall of 1969 and Spring of 1970 t,he PLATOadministered materials v x c uscd by approximately 20% of the studcnts enrolled in a special one-scmrstcr course for t,hose with weak high-school chemistry backgrounds. The diagnostic quizzes wcrc?presented t,wo weelis after the studrnts had uscd the int,roduct,oryand pract,icc sections of thc lessons. The st,udcnts from t,he selected quiz sections were cxpcctcd to attcnd t,hc PLATO sessions in addit,ion t,o thr usual ~vcekly1 hr lecture, 1 hr quiz session, and 2 hr laboratory. Although the PLATO sessions were held in t,hc cvming, attendance was very good, particularly for t,hc introductory segments of the lcssons. An analysis of t,hc record of the act,ivit,y of each st,udent shoxcd t,hat, thcsc lessons provided a means for each student to 1vork at his own pace and t,o receive the specific help he needed, thus fulfilling a major object,ive. Each student received a unique inst,ructional experience. The slower students rcquimd approximately t,hrce times as much time as the fast,er studcnts required to finish a lesson. The introductory material on chemical formulas was completed in forty minut,es by the fastest students while the slowest students required over 2 hr. I n the Spring term one studcnt requircd help eight, times with this segment, of the lesson, another needed help seven t,imes while five of thc seventeen studcnts needed help only once. Each studcnt had trouble at least once but in every case the use of the help sequence enabled the studcnt to solve the problem. In both semesters the students who regularly attended the PLATO sessions carncd higher course grades than those who were not given that opportunit,~. In the Fall term when 22% of the class used PLATO, 37% of the A's and 29% of the B's were earned by the PLATO group. In the Spring term two quiz sections taught by the same instructor were chosen for the study. One quiz section was given an opportunity to use PLATO for all three topics while the other was given a chance to use PLATO only for a special review session held just prior to the final exam. Eighteen students attended PLATO scssions on at least two topics, thirteen attended only thc review session and seventeen were unable to attend any PLATO sessions. The distribution of the course grades for these three groups shown in Table 2 indicates that the PLATO group again earned better grades than those without PLATO.
30 3 17
35
~-
All students were taocht b y the same
Figure 4. The computer is able to interpret chemicol equdionr m d to determine specific errora. In oddition to determining whot is unbalanced, the computer can detect the presence or obrence of specific species and improperly written chemical formulas. The order of the reactants ond is ignored ar ore all spacer.
4 22 5
62 6
(porecn!) (number) 2 (pement) 12 -
No-Plat0 --
7 39 8
2 11
0 0 2 12
Total number of students
1 6 0
O~ 4
24
18
13 17 --
instructor.
The review session which consisted of the diagnostic quizzes on chemical formulas and quant,ities from chemical cquat,ions was attended by thirteen of t,he eighteen studcnts who had part,icipatcd regularly and by the thirt,ecn st,udrnts who did not have PLATO-administ,cred instmetion on these t,opics. Thosc without PLATO-administered inst,ruction on these topics had participated in a mat,h review early in t,he semester and t,hus were familiar wit,h the operation of the terminal. The group wit,h PLATO-administ,crcd instruction scored significantly higher on both quizzes than those without the PLATO-administ,crcd instruction as indicated in Tablc 3. A t-test of the difference betuwn the mcans s h o ~ w dthat the probabilit,~of t,he difference bct,~vcenthe means of t,he t,wo groups on the quiz on chcmical formulas occurring by chance was less than 0.02. A similar t,cst shows t,hnt the probability of the group wit,h PLATO-administered instruct,ion scoring so much highrr on thr quiz on quantities from chcmical equations t,han t,hosc without. PLATO inst,ruction by chance alonr was less than one in a hundred. On the port,ion of the final exam covering these same two topics, the group which had regular PLATO experience again prrformcd bct,tcr t,han those who attended only the review session. Tablc 4 shows t,hc average scores (2) for bot,h groups. Table 3.
of Quizzes Administered by PLATO during Review Session
Results
-
-
-
f
" I
--
s.d.
Chemical Formrtlas (20 . ~oints) . Group receiving insbt~uction and review on PLAT0 13 16.30 2.60 Group with only review on 13.46 3.02 13 PLAT0 0.02 > p > 0.01 1 = 2.63 24 d.f. Qoantities from Chemical Eqoations (20 points) Group receiving iustruetion and review on PLAT0 13 13.00 5.99 Group with only review on PLAT0 13 7.230 3.68 24 d.f. 0.01 > p > 0.001 .-- 1 = 2.06Table 4.
Results on Final E x a m for Material Covered by PLATO Lessons
- -
~
-
n-
~
sld. - -
L
~
Chemical Formulas and Moles (24 points) Group receiving instruction and review on PLAT0 13 15.23 7.41 Group with only revlew on PLAT0 13 10.46 5.50 0.10 > p > 0.05 1 = 1.86 24 d.f. Quantitiesfrom Chemical Eaustiorrs (16 ooints) Group receiving instruction and review on PLAT0 13 13.85 2.27 Group with only review on 13 11.38 4.91 PLAT0 0.20 > p > 0 . 1 0 24 d.f. t = 1.64 Volume 48, Number 12, December 1971
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793
The above results are particularly noteworthy because the differences between the two groups were much larger on this material than on material not covercd by the PLATO lessons. On the first hour exam which was administered prior to thc PLATO lessons thosc who eventually used PLATO scored only slightly bctter than those who eventually attcnded only the review session ( t = 0.95, 23 d.f.). On thc portion of the final exam covering material which was not in the PLATOadministered lessons, the average score of thosc with PLATO-administered instruction was only 1.38 points (out of 108) better than those without PLATO-administered instruction. Thc performance of both groups on material not covered by the PLATO-administered lessons is summarized in Table 5. Eleven of the fifteen students who attended thc PLATO lesson on balancing oxidation-reduction equations scored the maximum credit of 10 points on that portion of the final exam. Only one other student taught by the same teaching assistant earncd thc maximum credit. The average score of the group that had PLATO instruction was 8.76 while thosc without PLATO instruction had an averagc of only 4.82.
Table 5.
a) Ilesults of First Hour Exxm (100 points) Gmop receiving instmetion 13 78.92 and review an PLAT0 Group with only review on PLAT0 lZa 76.25
The general attitude of the students toward the use of PLATO was favorable from the very beginning of the project and became even more favorable as the lessons were edited to permit more flexibility in the form of acceptable answers. The results of studcut responses to questionnaires and student comments indicate that the students liked the PLATO experience and that they would like to have other chemistry lessons offered on PLATO. They indicated that the operation of the machine did not interfere with their concentration on the lessons and that they received the hclp they needed. When asked to compare PLATO with other instructional media the majority of the students felt that they learned best and most easily from PLATO. The majority also expressed a personal preference for PLATO as shown in Table 6. The students really appreciated the opportunity to work at their own pace and to receive immediate fcedback in privacy as evidenced by the following typical responses to the question, "What do you like the most about PLATO lessons?" Being able to take the time I need to absorb and comprehend the material without inconveniencing another penon. One knows immediately if his answer is correct or incorrect. I just like doing things on my own without a teacher watching over my shoulder. If I make 8. dumb mistake I don't feel bad since only the computer knows.
Most students found nothing annoying about the PLATO lessons except the time a t which they were available, a reference to the evening class schedule. This problem will be corrected by the expansion of the PLATO system in the near future. Conclusion
It is clear that the use of the PLATO lessons achieved the objectivc of providing stimulating individualized instruction which has not been possible by other educational media. Those who used the materials performed better on exams covering the mat.erial in the PLATO-administered lessons than those who did not 794
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Journal of Chemical Educofion
7.96 5.96
h) Ilesult~on the Portion of the Final Exam Covering Material Nut Included in the Lessons Administered by PLAT0 (108 Points) Group receiving instruction 13 61.92 12.87 and review o n PLAT0 Group with only review on PLAT0 60.54 11.49 13 t = 0.29 0.90 > D >0.80 24 d.1. Onestudent absent. Table 6.
Students' Comporison of PLATO with Other Instructional Media
Text nest Most easily Least easily
1
Prefer Under other:
a
Worst
Student Attitudes
Results of Exams on Moteriol Not Covered by PLATO Lessons
Movie 1 3
I 5
6
Least easily Movie and TV Lecture & T V
Tv
Leoture
PLATO
1
14 12
TV
3 6
Other
3 1 2
Prefer Text N P L A T 0 Leoture & PLAT0
~ e x%nil t
have PLATO experience. The students readily accepted the idea of using PLATO and there was no evidence of hatred for the machine. An important feature of these lesson materials was that no artificial restraints were placed on the students. The computer was programmed to accept student responses in the same format as used in mrittcn work. Now that the computcr has been programmed to solve chemistry problcms and to ask specific questions about the problems, it is possible for the student to supply any number of problems. It will soon be possible for an instructor to provide each student with help on his homevork problcms by simply typing the data into the computer. The answers will be calculated and the propcr questions determined. Computer-aided-instruction appears to have the potential to become a valuablc tool for chemistry educators. We are anxious to explore its use on a larger scale in the near future. Acknowledgment
The author is grateful for the contributions to this study by Dr. Gilbert P. Haight of the Chemistry Department, Dr. R. Will Burnett of the Education Department and Dr. Donald L. Bitzer of the Computerbased Educat,ion Research Laboratory at the University of Illinois. Dr. Stanley Smith, Alan Illuirhead, and Larry Francis provided valuable suggestions and assistance with the chemistry and programming. Paul Tenczar and Richard Blomme developed the language (TUTOR) in which the lessons wcrc written. The students were selcctcd with the cooperation of Dr. Elizabeth Rogers who was the lecturer for the course. This research was supported by thc National Science Foundation grant GR-60, National Science Foundation grant GF-81, and the Advanced Rescarch Projects Agency under grant ONR-Nonr 3985(08).
