In automatic mode, the program picks the required number of TA's for the course from the top of the sorted list. In interactive mode, the top 10 choices are presented, with a preselected amount of detail. The operator can request information on any other TA, if desired; then the operator selects the TA's for the course. If no satisfactory assignment can be made, the program attempts to make a switch, by backing up through the courses already assigned until a TA is found who can take the present course. Then the program checks for any incompletely assigned TA who could take one of the found TA's previously assigned courses. Possible switches are searched until a satisfactorv match is found. In interactive mode, the operator is allowed to approve or reject possible switches. This procedure is followed until all courses are assigned. Then two output files are printed, as desired. The first is a data file. which can he edited and used as an input file for a later run of the program, so all assignments need not he entered manually again. The second is a print file that includes a summary list of assignments for each TA, a course schedule, including times, rooms, and personnel, and a list of assignments and a-schedule for each TA, used to communicate the results to the TA's. This program has been used successfully by us for several years, and has saved untold numbers of hours and prevented much aggravation. The programs, sample data files, and complete documentation are available from Project SERAPHIM on an Apple or IBM disk. The programs have not these disks or 1BM microrom~~u~ers,~hut been run on can be used as a means of transporting the programs to VAX
~ i n e r aChemistry l ~xaminationi Bernhard Binder2 and Timothy M. Maflet Southern Oregon State College Ashland, OR 97520 Whether conventional examinations are the best tools for ~romotingand evaluating learning in general chemistry has been a subject of much debate. One recognized improvement is repeatahle testing, which allows students to retake an examination for a hetter score. The tooics covered remain the same, but the individual questions ;ary. This approach has been recommended bv Moore and others ( I ) although additional instructor effort is required to produre and score additional test forms. Among the reported benefits are that "effort replaces student anxiety". The development of computer-generated, repeatahle testing described in this paper produced similar benefits without the instructional work-load once the system was operating. Test 'eneration utilizes the 7200question general chcmistry data bank developed by Johnson and others (21a3 part of the SOCRATES project. The entire hank has been copied from the original SOCRATES supplied magnetic tape to six 5'1,-inch floon\.disks with anadditional 1300 ofour .. .." toeether own questions. As a next step. has been developed (in Tur. proeramminz . ho-Pascal) to generace repeat.&le tests which can he admin~steredinteracti\,ely to students with access to MSDOS mlcrocomputers. hes system has been tried out in our general chemistry course during spring and fall 1986 using IBM compatibles. Experience with programming or microcomputers is not required. To prepare a repeatahle test requires about 20 minutes when utilizing the instructor's disk (named COMPOSE). Entering the command "COMPOSE" boots the menu-driven system and then a test may be generated. I t will he identified by TEST FILE and an appropriate descriptive 342
Journal of Chemical Education
6 16 DISKS)
Figure 1. Functional flawdiagram fw computer-generated examinations. Operating system: MSDOS. Language: Turbo Pascal. Memory: 256 Kbytes.
title (course and test number). Then individual topics are selected from a well-indexed tally (with close to 400 entries) together with the number of questions per topic and points to be awarded per question. Upon completion of the test, COMPOSE prompts retrieval of all the questions within each selected topic from the data bank and forwards the entire examination to a formatted disk named TEST. Two disk drives are rewired for this generation of repeatable examinations. The student's source of repeatable, interactive examinations is the TEST disk. If several microcomputers are available, multiple copies can advantageously be used for simultaneous testing. To get started, all a student needs to know are the hooting prompt "TEST" and how to insert the disk in a drive. For an averaee-leneth examination, a microcomputer requires only seconds io select the individual items randomly from the sub-hank. Once the first question is displayed, the time for completion of the exam depends mainly on how fast the student supplies the answers. After each response, the correct answer and the sums of the number correct and incorrect are displayed. The session ends with a performance summary and an optional entry in the computer or paper grade hook. Suhsequent repeat-examinations using the same disk may he taken as long as appropriate supervision can he supplied. When it was first announced to the general chemistry class, our students warmly welcomed this form of testing. One examination has been administered as an optional make-up for an in-class test. Most students were eager to try out the system because of its repeatability and flexible scheduling. A total of 68 individual test sessions were completed over a period of two weeks on three microcomputers. The result was that 33 out of 53 students achieved a better score than on the original examination. Other tests have heen generated for the purpose of voluntary review before taking the standardized ACS exam. These have been in heavy demand by seemingly motivated and enthusiastic learners. Many students have reported that their learning of chemistry has been significantly enhanced -
Author to whom correspondence should be addressed.
and have requested more extensive replacement of conventional tests. Although some glitches in the data bank surface occasionally (such as print or answer errors) the didactic benefit of enhancing general chemistry instruction with this transferable svstem amears certain. As Shown &the functional flow diagram (Fig. 1) the 5l/4inch MSDOS svstem consists of a COMPOSE disk for exam generation, a TEST disk (written by COMPOSE) for student use and the SOCRATES question bank spread over six individual disks. The SOCRATES index (called TALLY) for the 8500 items in the bank resides on COMPOSE. Before generating an exam the instructor should select from this index the appropriate question file number for each topic. Consequently, a hard copy of the TALLY file is certainly advantageous for efficient exam generation. Machiue-readable copies of the examination system may be obtained by writing to the corresponding author. Acknowledgment The authors would like to thank R. E. Seevers and Ed Williams for valuable technical advice and programming assistance throughout the development of this project. This paper was presented in part a t the 41st Northwest Regional ACS Meeting, June 16,1986.
Computerized Checking of Data in Undergraduate Laboratories D. A.
Alkens, R. A. Balley, and R. L. Strong Rensselaer Polytechnic Institute Troy. NY 12180
An aoolication of oersonal com~utersthat we have found to he v&ahle in the ;ndergraduaie laboratory is checkingof data for acceotabilitv. As we have emoloved this conce~t. the student enters the raw, measured data and receives & immediate evaluation in terms of acceptable/unacceptable-repeat. If unacceptable, there is generally enough time remaining in the laboratory period to repeat measurements as necessary while the apparatus is still set up and solutions are available. Such checking provides an impetus for improved technique and ensures that the results will be able to illustrate those principles that the experiment is intended to address. We frequently follow this checking program, which gives only yeslno answers, with other computer manipulations of the acceptable data. An example of a physical chemistry experiment to which we have applied this approach is that involving electrolytic conductivity. In this standard physical chemistry experiment (3-5). the cell constant of a conductance cell is determined by measuring the conductance of a standard KC1 solution, and the conductance of strong and weak electrolvte solutions (HCI and acetic acid) are measured over a range of concentrations. Such measurements can be made quite accuratelv. but thev can also be verv ~ o o ifr techniaues are carelesi. In our program, students "cieck their cell constant determinations by entering the cell number, KC1 concentration, and conductivity meter readings for KC1 and for the distilled water used in the solution preparation. The known cell constants for all of the cells are stored in the program, which calculates the student cell constant and compares i t with the appropriate value. Agreement within 1%is taken as acceptable. his approach has clearly resulted in an improvement in the quality of data appearing in the student's reports. In the semester preceding the use of this program, approximately 30%of the final reports received exhibited major deficiencies in the form of excessive scatter in the data or values differine from the literature value by 5% or more. Another 10%initial-
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ly reported data that clearly resulted from experimental blunders, such as mislabelling of solutions. The program eliminates all such problems. Repeated measurements have not been unreasonably burdensome, and students clearly spend more effort to get it right the first time. We are using similar programs for a vapor liquid phase diagram experiment (6-8) (checking refractive index values making up the calibration curve used for analysis), and two kinetics experiments (hydrolysis of t-butylchloride (9, 10) and neutralization of nitroethane (11,12)). The decision as to what constitutes acceptable quality results in a teaching laboratory is sub.iective. Except for the conductance experiment, where the standard is based closely on a realistic evaluation of likely sources of error and the students are second-semester iuniors with considerable laboratory experience, we have set our limits to reject the worst 5 to 1070of the results. Such a limit eliminates blunders and gross carelessness, without resulting in excessive requirements for repetition. Results from students with different levels of expkrience or with different equipment might require more or less restrictive limits. In addition, we do not insijt [hat all acceptable results be excellent: there may still be a range umhen the results are ultimately evaluat. of grades . ed for quality. A demonstration disk (IBM-PC) of these programs can be orovided if reouests are accomoanied bv a check for 55.00 to cover handlini costs, made payable to ~ e p a r t m e nof t Chemistry, Rensselaer Polytechnic Institute. Acknowledgment We wish to thank Rensselaer Polvtechnic Institute for providing support for the development of these programs under the Harlan and Lois Anderson Courseware Develonment Grant.
A Student-Generated Database for the Physical Chemistry Laboratory J. A. Wood The Polytechnic Queensgate,Huddersfield.HDl 3DH, United Kingdom
. .. Bv the time students enter ehemistrv courses.. man",~~ are quite adept at pmgramming. Students shmlld hnve o p p o r r u n i t w to use the,? skills within the chemistry rlsssnmn. One w q m dc, this is to give students pnjects that arp related t u the wntenr currently being studied. In this way, chemistry students can use their computer skills to produce software for future classes (13). This is a policy actively pursued with our undergraduate students. By the time they come to the physical chemistry laboratory sessions they have almost finished their basic programming course and it is an ideal time for them to put their newly gained expertise to use. A variety of programming and interfacing exercises have been set as part of this course, and a number of these have been developed into standard laboratory progams in later years after suitable, often minor. amendment. The one described here has proved very popular with students and combines an application of programming skills with an exercise in reference literature searching and data retrieval, the product being a useful database of phvsical . propertv - .data. At each laboratoiysession a pair of students is given the task of compiling a table of data from literature sources available in the departmental chemistry library. They convert this to aBASIC program and then transfer i t to a disk to form part of a growing collection of such tables compiled by other pairs of students, all the data being relevant to lahoratory exercises currently in use, for example, melting points of common solids, boiling points of organic solvents, densities Volume 65 Number 4
April 1986
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