Use of the Computer for Chemistry Instruction Robert Suder Portage Northern High School, 1000 Idaho, Portage, MI 49081
In these times of rising cosw and decreasing revenues, one must be able to work as etfirientls as wssihle. At the school system where I teach chemistry we have seen a drastic decrease in funds, resulting in many changes. Therefore, the teacher must he able to work smarter, rather than harder. Several years ago, I purchased an Apple I1 computer with an Eoson MX-80 orinter. Since I had oroerammine exnerience:adapting to (he Apple presented little difficulg fo; me. The nersonal comnuter has been the meatest invention for the teacier since the'chalkboard. I t has allowed me actually to increase my efficiency without compromising quality. However, one must be careful to do only tasks with the computer that actually result in time saving. Too often, the computer is used to accomplish tasks that can be done better without it. A
Gradebook In our school system, student grade reports are issued six times per school year. As any teacher is aware, considerable time is needed to determine grades and, because of the sheer number of grades being calculated, errors will inevitably result. Therefore, I decided to use the computer as the gradebook. This allowed me to compute the grades for all my students in amatter of minutes. At the end of each week, I spend about fifteen minutes entering scores into the computer. When the grades are due, I simply enter the grade cut-off point and the computer determines the grades. Then I have the grades transferred from the printout sheets to the school's report card sheets by my student assistant. My actual time involved in preparing grades is a few minutes, rather than hours. Since I have extensive programming experience, I decided to write my own gradehook program, rather than buy a oackaeed one. In this wav. to fit .. I could design the oroaram . .. my needs exactly. Admittedly, it was a considerat,lv amount of work. hut well worth it. Ms zradelrmk Drozrum will wrform the foliowing:
NAHE
ABSENCES
POINTS
GRAPE
ADRRS J
A-
DOE J
B-
GARY R JONES M RILLER R PHILLIPS F SMITH J TAYLOR S
A C
WHITE H
Ct
B Ct
H* C
POSSIRLE POINTS -- 263 FAILIHG POINT --- b@ b
6RROIN6 SCALE
record scores record absences determine test s m r e averages determine tdnl pdnu for earh s~udenr determine lerter grade ior earh rtudent determine the number of each grade given per class allow for addition or deletion of students permit either screen or printer display (see Fig. 1) allow for easy changing of information The records in the program are stored sequentially on the disk. An added advantage of the program is that a student is able to determine his or her grade a t any time during the marking period. Therefore, he or she knows how hard to work in order t o improve the grade. Naturally, the program must have a security system that will permit the student to check only his or her grade, not change it. I use a password system that prevents the unauthorized modifying of grade records. The password uses control characters which cannot be seen hy listing the program. Chemistry Laboratory
The microcomputer is also very useful in the laboratory. Too often, the student simply performs the experiment, rec-
FkILlNG SCORE
-
60 B
Figure 1. Sample printout of computer gradebwk
ords data, and has no idea if the experimental results are correct or not. The student generally does not learn whether the experiment has been done correctly until the graded experiment write-up is returned. Therefore, I have written a number of programs that will permit the student to check his Volume 61 Number 3 March 1984
243
or her exnerimental data rieht in the laboratow. The student the experiment, enters the data intothe computer, and then the computer informs him or her whether the data is good. If it is not, the student knows to repeat the experiment. Since I began using the computer in the laboratory, the work of my students has improved considerably. I have also attemoted to have the student first type his or her name before ent&ng any data. The idea was to &ord the student's name and data, use the computer to calculate the experimental results, and save all this information on the disk. When checking lab reports I would he ahle to recall the information from the disk, and then compare their calculations with the computer's. This should make lab report grading very it has not worked out that way. The prohlem easy. is that there is only one computer available and lab periods are only one hour lung. Most students ha\,e no typingskillsor computer experience. A nm-typist may require several minutes-iust to tvne a name. I was findine that most of the students were not working at their lab stations, but waiting to use the computer. Having more computers available or more lab time would help to solve the prohlem. The computer also can he used t o simulate experiments. This is especially appropriate in cases that require special, or expensive, equipment or chemicals. One such simulation which I have written is adapted from the classical pressurevolume experiment.' After the student types his or her name, the computer graphics show the apparatus (Fig. 2). Pressing the return key changes the applied pressure, which causes the corresponding volume change. The computer will randomly eenerate different values for each student; therefore, each will have different experimental data. In addition, the computer will calculate the rorrect rxpt,rimental result* and record this and the students'namt.sonthedisk, making it nsimple matter to retrieve rhc information and (ompure with the studrnts' results. Students are required to show their calculations in their lab reports. However, by encouraging them to check their calculations with the computer's, they will he ahle to investigate their mathematic computations and hopefully remove any errors before submitting their reports. The programs I use do not show the students how to perform the calculations but simply provide them with a computed result. Because of the verv" easv - access to the Apple's .. input ports, i t is a relatively simple matter to interface it with ~ a h o ~ a t o r y instruments. Usually all that is required is an analog-to-digital converter. A-to-D converters that fit directly into the slots can be purchased for about $100.2 A less-expensive alternative would he to use the analog inputs in the game control^.^ One application of interfacing would be to provide a digital readout of analog devices, such as a Spectronic 20. I t is very easy for students to read absorbance incorrectly because it reads backwards on the meter; however, they ca-n check t h ~ i meter r rcadinrs with the digital readingsdisplayed nn thecomputer. . It is also possible tosave the experimental results on disk to check the students' results. The computer can he used for pre-lab quizzes. I have found that most titration errors involve reading the huret, and, therefore, I designed a quiz that will simulate a huret (Fig. 3). The volumes are selected randomly by the computer. If the student has read the huret and answered two questions correctly, his or her name will he stored on the disk. I can then determine who has passed the pre-lab quiz and is therefore ready t o perform the experiment in the laboratory. A modem allows one computer to communicate with others
c ow ever,
~~~~~
.~ ~
~
. A
using the telephone line, which enables one to contact chemical information services such as CAS ONLINE. A very valuable exercise is to have the student perform a compound search using this facility, . Communicating with the Student When writing programs for student use, one must realize that very few of them have any computer experience. The simple instruction "ENTER NAME" will confuse many of them. I t would be better to use "TYPE NAME, THEN PRESS RETURN." Also, the numhers one and zero are confused with the letters 1 and o. Numerous error-trapping routines are required. After the students enter their data, one must make provisions for the correction of errors. I use the statement:
CHECK YOUR DATA. IS IT CORRECT (YIN)? The prohlem that arises is that some students will type "Y" and others will type "YES." Therefore, the program should only look for the first letter. Also, some students will type "T" or another letter. The program should he ahle to handle this prohlem. There should he no provision for exiting the program other than hy special commands known only to the instructor or by turning off the computer. Assume that a student has finished
Figure 2. Pressurevolume simulation.
1r5
I-
I
IL
Question 1 h t is the buret reading in ml?
Diet.?,P.. Tellefsen, R., Parry, R.. and Steiner, L., "Chemistry ExDerimental Foundations: Laboraton, Manual." Prentice-Hall. Enalewood cliffs. New Jersey. 1975. John Bell Engineering, Inc., 1014 Center Street. San Carlos, CA 94070.
Deininger, R., and Berger, C., incider, 74 (January 1983). 244
Journal of Chemical Education
Figure 3.Titration simulation.
his turn at the computer, and the followinginstructions appear on the screen: (1) I'KKSS (KETI'RN) FOR ANOTHER SET OF DATA (2) PRESS (E, TO EXIT L'KOGKAM
Option (1)should be selected so that another person can use the computer. However, since most students have no idea of what exit means, they will select this option when done. The instructor will have to reload or rerun the . oroeram. On the other hand, there are the hot-shot programmers who like to get a listing of the oroeram and then change the commands. ?herefore,if possikle,ldisable the reset ke;.4 Database System
A database oromam is similar to a comouterized index card system. I t wilfstore information for easyretrieval. There are manv database Droerams available. Examine several before making a decision. One use for the database program is stockroom inventory. Since we have a large chemical stockroom, computerization seemed the logical choice. One can have information concerning the name of compound, class, amount, etc. One of the features of database systems is their ability to sort and search. If one wants to know what bases are available in the stockroom, the computer can be instructed t o search the base classification and all these com~oundswill be referenced. Another advantage of the computerized stockroom is that one has ~nstantaccei;; to the chemicals that are available. Since I do not have an office in school (it was converted into a classroom). all mv reference hooks are a t home. If I find a promising kxperiinent that I would like to try, I can easily check mv comDuter listing - to see if the required chemicals are availablk. . Another use of the database program is to record student data, such as home phone number and hook number. If a student leaves his book in class, I simply have the computer do a search to find the owner. Also, one can keep a permanent grade record of the students. One problem with the database program is that a considerable amount of time is needed to record all the information. I t is very helpful if one has a student assistant who is able to type. When selecting a database program, be certain that it uses machine laneuaee for sorts and searches. The first oromam I tried did not, G d an hour was required to sort 175chem~cals. Mv nresent database nromam can accomnlish this task in a . few seconds using machine language. A
Word Processing
The term "word processing" is computerese for typing. The word processor is probably the most used progam that I have. With it I can write letters, tests, and experiments and edit them as needed. Once satisfied with the document, I can have it printed out. The document can also be saved on disk if I desire. Since I am not able to purchase textbooks for my organic chemistry class, I must generate most of the written materials used. The word processing capability of my computer has nroved to be a valuable resource. esoeciallv when I am nreparing lab experiments. Once I typethem, they are save: on disk and uodated as needed each vear. I like tohgivemy students as many practice problems as oossible. and it seems thev are alwavs askine for more. T o handle this demand, I prepare a master worksheet using the ~ word orocessor. and need onlv to add new data to D I O ~ U Canv subsequent wdrksheets. ~ o ; e x a m ~ l eif, I am writing a molaritv" nractice sheet.. I tvnicallv . ". " varv" onlv" the names and amounts of the given substances. The same techniaue can be used to write tests. I had found even before I begad using the word processor that my tests follow a similar pattern year after year. Thus, with the word processor, I have freed a considerable amount of time that can be used more productively elsewhere. I typically take an old
test and make numerical and nomenclatural changes. Thus, the main body of the test remains the same; this is especially useful for preparing makeup exams. There are several features to look for in a word urocessor. Firit, thwe must be provisiun for subscripts and superscripts. Without this abilitv. ".it is difficult tu write formulas or exm). nents, however, it may he inconvenient to use these features hecause special printer codes are required. My word processor uses the ESC key for upper case, and control keys for subscripting and superscripting. Writing the formula for sulfuric acid uses the following key sequence: ESC H CTL B ESC 4 CTL B ESC ESC S CTL B 1 2 CTL B ESC 5 ESC S ESC 0 CTL B ESC 4 CTL B ESC ESC H CTL B 1 4 CTL B ESC 5
I t is hardly worth the trouble. Second, the screen disnlav should indicate exactlv how the document will appear on the printed page. One m i s t know where the margins and the end of the Daze . . will he. When I wrirr aqurstion on a test, I leavespace for th~cnlculationand answer. Therefore, I must know exactlv how it is formatted and where it will be on the page. Next, i t is very helpful if one can see an entire line of text. Since my computer has only a 40 column display, and the printer 80 columns, this could be a disadvantage. There is hardware available that will give an 80 column display but this is often expensive. My solution has been to purchase a word processor which uses the computer's hi-res graphics to show 70 columns and lower case. I have been using the Magic Window I1 word orocessor bv Artaci and have been extremelv pleased. My onl;complaint"is that it is protected software; it is not possible to make a back-up copy of it. The company does offer a liberal warranty, but if for some reason I accidentally damaee the disk. I will not be able to access anv of mv documents-until a replacement disk arrives. T o orint numerous conies of anv one document i t is necessary tb make dittos because we do not have access to a photocopier. There is a ~ r o b l e mhowever. , A dot matrix orinter doesnot impact h a d enough to make a ditto. ~ h e r k o f a x " dittos of the original can he made, but this does not alwavs produce a clear copy. Therefore, to get around this problem I make a ditto using a Thermofaxe master directly in the minter. In order to obtain hest results I use both the douhle strike and emphasized printing modes. In addition, I remove the printer ribbon so that the pins strike directly on the Thermofax master. One final oroblem is that mv orinter is tractor feed onlv. and through. One solutio; i s to ~ h e r m o f a x dittos i will not taoe the ditto to the naoer. A better solution is the ourchase o f a Paper Porter.5 'kh:ls is a plastic sleeve carrier'that will allow regular paper or dittos to go through the printer.
Gs
VISICALC@ The VISICALC" program is an electronic spread sheet. I t can be used to make forecasts or projections as well as store data. We have used the program to perform calculations with large amounts of data. A number of teachers use this program for their gradehooks. Recently, we have used Visicale for contract negotiations. The current salarv schedules were placed in the program; then, using the projection feature of the program, our school system could see how the values would change if certain percent pay increases were granted. The administration may want to use Visical@to make projections of student counts, costs of utilities, etc. Visicalc" is probably one of the most important programs ever written for the comnuter. I L v e described a few ways in which the microcomputer can be helofnl to the classroom teacher. I would never want to he withoit one again. Soflalk. 44 (March 1983). Beeline Services, 5718 Pondelosa, Stevensville,MI 49127
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