for the transformation of "fractional" t o orthogonal coordi- nates.

Several extensions to the program can be forseen, including the use of an Apple I1 "shape table" to circle or label atoms and for better data base handling. Printers are available to reproduce the Apple I1 graphics pages, and even better results could be obtained with a digital X-Y plotter. However, these extensions detract from the concept of a simple low-cost sys- tem, readily usable by inexperienced operators.

Proeram PRO.JECT-X. Written in Aoolesoft BASIC. 323 state-

so that operation on other microcomputers with comparable graphics facilities is possible. Copies of the documentation are available, handling charge $5, or with cassette, $10 (surface mail). International money orders should he made payable to Dr. R. Keat at the above address.

CAI Programs in BASIC and an Associated MATH Subroutine

Robert Hunt Anderson Western Michigan University

Kalarnazoo, MI 49008

Four new BASIC oroerams have been DreDared and tested by student use for more &an a year. These interactive CAI programs that can also be converted to a mode that will gen-

erate quizzes or homework assignments with separate answer keys. The latter method of use greatly decreases student ter- minal use.

CH20.BAS consists of six problems on the metric system chosen a t random from the following seven types:

1) Conversions between units of the same randomly chosen quantity with different prefixes.

2) Conversions between liters and meters cubed. 3) Conversions between squared or cubed units of length. 4) Density of water conversions between grams and ma. 5) Density of water conversions between grams and L. 6 ) Product of two lengths with random prefixes. 7) English to metric or conversely.

In all of the types, the metric units may have any of the pre- fixes chosen a t random. Also, each problem type has three or four randomlv chosen suhtvnes. For examole. under tvne 1 the first subtype goes from ;prefixed quantity t o its root ;nit with no prefix, the second is the converse of this, and the third subtype goes from a given prefixed unit to a sought unit with a different prefix. Each type is normally chosen only once, but it is possible to request just one type, in which case six assorted problems of the one type are generated. The variety and use of prefixes in CH20 is greater than in most CAI programs and provides a challenge to all but the best students. When run interactively in the usual CAI mode, up to four levels of help or hints are displayed on the terminal for wrong answers. The last help for each question is the complete setup showing all conversion factors and units.

Guidelines for Short Descriptions of Computer Applications in Chemical Education for Publication in the JOURNAL OF CHEMICAL EDUCATION as Bits and Pieces

The purpose of Bits andPiecesarticles is to disseminate as broadly as possible information about computer applications in chemical education. Because space in the J o u n ~ a ~ is limited, authors are requested to be as brief as possible, providing only information that will be needed in order for a reader to decide whether or not he is interested in obtaining more detailed information. Program listings, circuit diagrams, specific documentation, and so forth are best handled as supplementary material sent tothose readers whose specific interest requires it. Short descriptions of computer appli- cations should not exceed three double-spaced typewritten pages in length and should not include more than a total of three (figures and tables). Each part (a, b, . . . , etc.) of a figure or table will count as a separate figure or tahla

Authors should address as clearly and concisely as possible:

(1) The purpose or objective of the lesson or laboratory experience for which the computer application has been designed. In what course or courses mioht the comouter aoolication be used. and what effect ~ ~~ - , . is it supposed to have on students?

(2) The material that is presented to a student by the computer and the kinds of responses students are expected to make. What does the sNdent have to do? What doesthe computer do? What is new, unique, andlor pedagogically useful about the computer application being described? How does the computer application fa into the chemistry curriculum?

131 Availabiiiw of the cornouter aoolication. A minimum reouiremem for . . p.b icarm s W.1 me sumor oe w l ing lo make ava lab c to an, reme8 H ~ O nqu res enoLgn specific nforrnawn so that tne reaaer can a... p a l e tne a d o r s appl car on -s.a I y m,s wo..a onrow? a program listing, sample execution, and perhaps documentation for soflware and a circuit diagram for hardware. Such materials must be submitted for review together with the manuscript that is intended for actual publication. Authors are encouraged to make available machine- readable versions of programs, but this is not a requirement for oublication. 7~~ ~ ~

a An offer of a free progranl listong can gpocal) result n 700 IC~.~SIS ma1 Ine autnor must process am pa) postsge torelurn A minimal charge for listings, documentation, andlor ma- chine-teadable copies wili usually separate the merely curious from the truly interested. but a charge requires that the author specify clearly how and to whom payment must be made (check or purchase order made out to John Jones, etc.). The authpr wili also have to arrange to handle incoming payments.

b. For machine-readable copies the author should specify the medium (punched cards, paper tape, 7-track or Wrack magnetic tape, magnetic-tape cassette, floppy disk, etc.). and how the information is encoded (026 or 029 punch cards); ASCII or EBCDIC code. record and block sizes. information densiN (SO0 or 1600 Bpi). nLrnoer of fi es. elc on magnet c :ape. recoro nq conrent on for tape cassere or i uppy a sn

c f rvilders are .na> e lo oolaln L p p emenia) mster a s irom an authw, copies will be retained by the Computw Series editor and supplied by the editor toany reader who requests them at a cost of $5 for duplication, handling, and postage.

(4) Transportability of the computer application. Thisbreaks dawn into three cateaories lsee J. CHEM. EDUC. 56. 146 119791 for detailsl: - .

a himware. lsabp cai narawaretgraphicr termma. m crocorn. pbler Fpecra cwcb I, elc. necessar) for r-nning the prosram7 11 90 =,pecil) clearl) oy manufacturer an0 mode n,moer On what make(s) and model(s) of computer has the program been run? How much memory is required to run the program (8K 36-bit words. etc.)?

b. Software: In what language is the program written? Has an at- temd been made to follow ANSI (American National Standards

~

lns!.!~ei 01 otner trnnsportao 1, rtanoarns? c Doc.mentat an rloa man) comments are n me program lwt-

'"97 Are a flowchart and sample exec"! on a m l;me7 1, there separate written documentation? Is there pedagogical docu- mentation that specifies subject matter. instructional objectives, and pedagogical techniques?

terns 3 ano 4 auoe neea 0cc.p) on, a slog e paragrilpil nil plogram aescrlphm Tne lo1 on ng emmp.e no cams how mrcn nformill an can oe summarized concisely:

Program TISIM-Interactive ANSI-standard FORTRAN, 75 statements. 75 comments. Students run TlSlM via Tektronix 4010 graphics terminal. Execution requires 3K 36-bit words on a DEC10. Documemtion includes listing, flowchart, and several sample executions; students are given in- structions via the terminal at execution time. Copies of the listing and documentationavailable free. Nocarddecks, but will supply pragramand Sample executions on your Wrack. EBCDIC. magnetic tape at 800 Bpi for $5 postage and handling charge. Send a blank tape witha check for $5 made out to: Dr. Susan Smith. Department of Chemistry. Your Uni- versity. Anywhere 12345.

Volume 59 Number 2 February 1982 129

The second program, CH40.BAS, has the three simple types of densitv oroblems: findine mass. volume. or densitv. Three - . "

levels of help are provided. The third program, CH251.BAS, asks three types of ideal

pas law problems. The first type has four subtypes, which are lo ~olve-for volume. nressure. temoerature. or amount of eas.

" - ". quantity of gas may be given in moles or grams. In the latter case. the name of the eas is eiven and the user must find and use the molecular weight. he temperature may he in degrees Celsius or kelvins. The volume may be liters, milliliters, or m3. The pressure may be in atm, mm-Hg, torr, or pascals. Each of the above is chosen randomly with agreater orohability of choosing the more common units in each case. A difficulty parameter may be set to any of four levels.

The fourth program, ATSTR.BAS, asks the following eight types of problems:

3) Names or notation for the four quantum numbers. 4) Meaning of each of the four quantum numbers. 5 ) Permitted values of the four quantum numbers or number of

electrons in a shell, subshell, or an orbital. 6) Bohr theory, its qualitative assumptions and E, = hu. 7 ) Bright line spectra, c = Xu, or AE = hv with numbers. 8) Bohr theory of hydrogen spectra using Rydberg's constant or

the ionization potential.

The first four types are not suited for any help levels. Most of the rest are suited to no more than one level of heln.

In all of these CAI programs the student's grade is given to him at the end of the run, and it is also written in a disk file for the instructor. Certainly the first three programs are suitable for use hy high school students, and all are suitahle for first- year college science students. The average college student could benefit bv usine them for review even after the first vear. Actually, thesebave ieen added to a collection of 20 o t h e ; ~ ~ ~ oroerams (4). . .

111 ('H ioaild partiallnrlv i n ('H251, asnvll ,I. 111:111y(d the uthu ('.A1 1mgrams in cur c o l k c ~ ~ ~ m , 4 numt r i d rdculati~m is rcquind to uhtain the anaver. \\'it11 thr prwalci~ce 01 pr~ckrr calculators, this vr,,vidcs lirtlr I I ~ o I I I I . ~ , hut a hlA'I'tl aub- routine ha; beenwritten in BASIC thatpermits input of an entire arithmetical expression, called S$, in place of a single number requested for the answer. The MATH suhroutine then analyzes S$ and converts it by the specified calculations to a single number that is returned to the main program as the value of the variable S. This is then checked for correctness. 'l'hia ,ul~r<tutitw elitilitidtes the uav o r :in ~ X I I ~ ~ I I c;tlcdator and rivt,s n printed rrcord or tht. wprl..wn iiiput a1mx ulifh . i t s answer. -....- ~~ ~-

The MATH subroutine (lines 9000-12820) may be woven or included in anv BASIC oroeram. I t occuoies 19K on our disk and so i t is ;ecommendei that i t be woven with each oroeram before runnine rather than heine oart of each oro- . - -. gram. This saves disk space. The arithmetical expressions are now limited to 100 characters in lenath and can only contain numhers hut may include E-type f&at. Nested parentheses and the operations +, -,*,I, and **, or t for exponentiation are permitted. The common functions (SIN, COS, TAN, COT, ATN, EXP, LN, LOG10, and SQR) are allowed. Other func- tions could be added rather easily if they were needed. A space or other illegal symbol results in an error message with a re- quest to retype the expression.

A listing and sample runs of these four programs and the MATH suhroutine will be sent to anyone for $2 to help cover postage and preparation costs. If desired we can put them on your magnetic tape and return i t to you for the same $2. For $15 the programs on half-inch magnetic tape will be sent to you. I shall be happyto answer any questions concerning them or correct any errors which may turn up.

A CAI Preparation-for-Chemistry Course James W. Beatty and Earle S. Scott

Ripon College Ripon. Wisconsin 54971

Five years ago we decided we needed a course to prepare about 30% of our students for our general chemistry course. These students have inadequate backgrounds in chemistry, hut most of all thev have lost confidence in their ahilitv to - ~ ~ ~ - ~ ~ ~ ~ ~ ~ ~. solve mathematical problems. The purposes of the course are to restore their confidence, to teach them how to use electronic calculators, to make correct calculations with ease, and to learn the fundamentals of uroblem solvina in chemistry. Onlv basic ideas and calculations are stressedbecause we want to prepare them for a general chemistry course and not to teach them general chemistry.

A text of about 100 pages and nine computer assisted in- struction (CAI) programs were written. The book consists of ten chapters. There is a program for all hut the first chapter, which is on the technique of problem solving. The comple- mentary CAI programs for chapters two through ten are: (1) Mathematical Review, (2) Dimensional Analysis and Graphing, (3) Chemical Formulas, Molecular Mass, and the Mole Concent. (4) Densitv Calculations. (5) Ideal Gases. (6) . , . . . . . Empirical Formula and Percent Composition, (7) ~ o l & and the Preparation of Solutions, (8) Nomenclature, Including Common Ions, and (9) Balancing Chemical Equations. The programs parallel chapters in the text and have similar names. The programs are independent of the text in the sense that anv eood chemistrv oroblem book could be used. Our text is . . limited by design.

Versions of the moerams are available that will run on all . . ( 'ornm~Iure tnivrt~~.otiipl~ters having ah "I' Ithhl. Irom the small-ke\.btmrtl IJfZl' Wrll to thr i'HV lo'cs.32. Tht ~~r t r<r ; i t~~> are straightforward drill programs, which a student can go throuah in about 15 minutes. Surorisingly, students take notes without encouragement. At the;equ&t of the students, the programs give a score at the end. Students routinely repeat a program until they achieve a satisfactory level of perfor- mance. Numbers and chemical formulas in problems are se- lected randomly by the program.

The PET was selected because it is self-contained and makes it easy to present chemical formulas in their desired form, such as Fe(N03)~ and Mg2+ using superscripts and subscrint,s. and uooercase and lowercase letters. Some of the . , . . programs give background information. If an incorrect answer is entered, the correct answer is given with details on how to calculate it. The programs do not offer assistance in the sense that manv believe a comouter should. Memorv limitations. writing time limitations, and a philosophy of individual per- sonal instruction encouraged us not to undertake this au- pnach. 'l'heoiricc of tht. m.trur~or iiadiacent rothv,.oml~~itt.r lalxmrurs, and lit. is amilahle fur cun,~ltati<~tl. Tlirw I ' W i adequateiy serve 20 students and would serve a greater number if times were scheduled. An example of a problem that we helieve is best handled by individual instruction is the following. Students frequently enter 6.022 X loz3 in their calculator by punching 6.022, punching the times key, punching 10, punching the enter exponent key, and then nunchine 23. Not realizine that thev are off hv a factor of ten. .~~ ~ u

they then perform subsequent ca1c;latious. They helieve that the computer is correct and will attempt to prove i t by re- peating the calculation. We believe these programs can be used most effectivelv where individual attention is available within a day br two.'

A student must receive less than 50 points on the Toledo Placement Exam to enroll in this course. Students taking this course receive on the average a grade one letter higher in general chemistry than they would receive if they had not selected this option. An additional benefit to all is that a student often finds out painlessly that science is not for him.

130 Journal of Chemical Education