John W. Moore and Ronald W. Collins Eastern Michigan University Ypsilanti, Michigan 48197
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A Tool, Not a Gimmick An introduction to computer applications in chemical education
This is the first in a series of articles that attempts to delineate the current state of the art o f computer usage in chemical education. The articles will appear regularly under the editorship o f John W. Moore and Ronald W. Collins. Although each o f the articles will describe the latest developments in a given area of educational computing, the needs and background o f readers who have little or no computer expertise will be accommodated. The editors'intention is to be, as one of the new computer-hobbyist magazines bills itself, "Understandable for beginners. ..interesting for experts." This introductory article includes background material on comnuters that will be of value in understanding subsequent papers in the series. It also discusses the advantages and problems of implementing computer-based educational materials a t locations and on machines for which the materials were not originally designed, and provides a scheme for classifying computer applications in chemical education. Subsequent articles will treat these categories of computer usage, as well as some of the tools needed to implement them, in detail. in chemical education The field of comuuter au~lications .. is currently a very exciting and rewarding one to be associated with. The rate a t which new discoveries and developments are being made is accelerating rapidly, and the costs of equipment and time needed to acquire and use computers in the classroom continue to decline. New faces and new ideas are entering the field continually, while many older concepts have come-of age and are making substantial contributions to chemistry instruction. At the Fifth Biennial Conference on Chemical Education last summer. for examnle. . . more than one paper in five included some computer application, and more than half of the workshops and birds-of-a-feather sessions involved computers. We are a t a time of transition from the comDuter as a curiositv, usable onlv bv those in the know, to the computer as a tooit'hat everyone can and should employ, a t least occasionallv. The increasing number and sophistication of computer applications and their rapidly broadening constituency within the chemical education cim&nitv has increased the demand for information about computers and computer methods. Anticiuatine such a demand. the Division of Chemical Edu. cation set up a Committee on the Role of Computers in Chemical Education in 1972. The committee was c b g-e d with collecting, evaluating, and disseminating information on the manv. wavs - that computers were being used in the chemistry curriculum. ~ e c e n t l ;this committeewas renamed the ask Force on Computers in Chemical Education. It consists of 30 persons whoseinterests span nearly every kind of instructional computing and currently is chaired by Clare T. Furse of Mercer Universitv. Durine" the oast half dozen vears the committee has sponsored, organized, and taught more than a dozen Workshops on Computers in Chemistry a t national and regional ACS meetings. T h e committee also publishes a newsletter six times a vear (free of charge to members of the Division of Chemical ducati ion, $3 fo; three years t o others). 140 / Journal of Chemical Education
Each of the editors of this series has chaired the computer committee for a three-year term, and most (hut not all) of the authors of subsequent papers are current membersof the Task Force on Computers in Chemical Education. To a considerable extent these articles constitute a report by the computer committee on its perception of the current state of the art of computer-based chemical education, and they offer a means of disseminating information about computer-based chemical education to a broader audience than was possible in the case of the committee's previous activities. Both editors and authors have set a number of goals for each article. These are 1) To build from simple beginnings up to the state of the art. 2) To define and explain jargon and acronyms whenever these cannot
be avoided entirely. 3) To provide information and examples that are as specific as pos-
sible. offerinnnuidelines and expert ooinions reeardine the best approaches tbdifferent types of'compker application;
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About the Editors.. John W. Moore received his AB from Franklin and Marshall College and his PhD from Northwestern University, concentrating in physical inorganic chemistry. He is the author olnumernus publications in inorganic chemistry, chemical education, computer applieations in chemistry, and environmental chemistry. He has also produced numerous audio-visualteaching aids, including films,overhead projection transparencies. and computer graphics. John W. Moore Ronald W. Collins received his BS from The University of Dayton and his PhD from Indiana University. He is currently Acting Head of the Department at Eastern Michigan University. The author of numerow publications on the role of the computer in education, and co-author with Dr. Moore of a general chemistry text, he has been active in presentmg many seminars,coursesandworkshops all over the country on using computers in teaching. Both Dr. Collins and Dr. Moore were the recipients of the Distinguished Fac- Ronald W. Collin! ulty Award at Eastern Michigan University this year.
To summarize pertinent features for selected examples of each twe .. of comnuter-based svstem. 51 To dwcrihe sourcca of working nmputer programs and ihr nm ditions under which such pnqrams may be ohrnrned. x w r r a 01 more detailed 6 ) To indude n .wleuted hihlmgraphy information.
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We hope that these goals can he met, and that you will find in this series a fneful overview of the manv roles of comnuters in chemical education. Before proceeding we offer one caveat on hehalf of all authors in the series. Computing is a wide-open, rapidly developing field, and no one can keep abreast of everv new development. ~ ; y i nto~he as specific and utilitarian as possihle offers the corollary possibility of being rapidly outdated, or even just plain wrong. Do not forget that there is no consensus on many of the topics which we will discuss and that what we offer are opinion;-expert bpinions, of course, and based on many years' experience, hut not necessarily on revealed truth. If all of us knew all of the answers, there would he little need for this series of articles, and there would he no excitement whatsoever in computer-based chemical education. What Can Computers Do? Computer applications in chemical education cover an ever broadening range and consequently are difficult to categorize. Nevertheless,in.this section we shall attempt to classify and describe briefly the many roles computers are playing currently in chemistry instruction. Details will not he given here because most of the categories we identify will he descrihed completely in subsequent articles. Computers can play a dual role in the chemistry curriculum. Computer programming, numerical methods, digital electronics and laboratory automation, microprocessors, and computer-based information ~rocessine.storaee. and retrieval are all subjects that many chemists m i s t lea&ahout as part of their training. Thus many courses that teach about computers have evolved. On the other hand it is possihle to teach with a computer, using the machine as part of the delivery system for the subject matter of a course.. These two aspects of computer use are not separable in practice. A student who is taught with a computer learns a good deal about computers, and to learn about computers a student should he taught with a comnuter. The main thrust of these articles. however. will he in'the area of computer-aided instructibn (CAIDI)teachine with a com~uter.What we sav about comnuters will he inteided mainlyto help you to teach with a codputer. Another basis for classifvina computer a~olicationsis the way in which the romputr;in;erarts with the student. Computer-asiisted instructitm (CAI) involvcsa dirrct, conversational dialog. The computer is programmed to present course material, ask questions, and check answers, varying its presentation on the basis of the student's resnonses. Recomizine " student inputs, evaluating them, and jumping from one part of the sequence of instruction to another as a consequence is the most difficult aspect of CAI. If this condition is relaxed and the comvnter nrompts hut does not tutor. the instructor/programher's jbh is much easier. Such p s e & i o - ~ ~can ~ still provide important instructional benefits. Another type ofjnteraction occurs when a student uses a computer as a tool or aid in solving a particular prohlem. Here there is less (or even no) prompting by the computer, on the assumption that the student has studied directions for using the c o m ~ u t e rnroeram. Such non-tutorial comnuter annlications ~NTCA)are valuable because the ease and rapidity with which a comnuter can calculate allows more lahoratorv data to he processed by more sophisticated methods. I t also permits a,greater range of more realistic prohlem assignments (such as molecular orbital calculations for reasonahly large molecules) to he completed within the time available. In some cases a student may have no direct contact a t all with a computer. In addition to scoring exams and grading laboratory results, computers can assemble and print prohlem
sets. ore-lab assimments. and tests. Each test or assienment can be individuakced by random selection of questiok or by randomlv filling blanks in a skeleton auestion. Comnuterassistedtest co~struction(CATC) allo& repeatable testing and greatly reduces a student's urge to copy results from a companion's paper. A relaled'technique is computer-managed instruction (CMI), in which course records are stored and monitored continuously by computer. Feedback is provided on each student's and the entire class's progress through the course, and directions for using specific supplementary or remedial materials are made availahle based on student performance. An important aspect of computers is that they can imitate almost anvthine. Com~uter-enhancedlearnine via simulation (CELSII~)incrudes Gograms that produce Zata from which students can discover new relationships or to which students can apply data reduction techniques: when the products of chemical reactions can he predicted, a computer can simulate synthesis or qualitative analysis experiments, allowing students to obtain much more experience of what reacts with what than there would be time (or monev) .. for in the laboratory. Simulation ran be an adjunct r o most of the computer annliciltions that we have alreads mentimed. and ir is also thc basis for what are called seriousgames. s he competition engendered hv keevinascore on how well an unknown is solved, Tor example, is an important motivating factor. A great man; simulations are enhanced if graphic (as opposed to verbal or numeric) results are provided. Computer graphics is therefore a valuable tool that can he applied to many aspects of instruction. This section has defined terminology and acronyms (CAI, CATC. etc.) that we will attemnt to use consistentlv thruughout rhis series uf articles. You should note, hoaevrr, that the same acronvms mav be defined differentlv elsewhere. (CAI, for example, & often "sed in the all-inclusive sense that we have indicated hv CAIDI). Indeed. looselv defined acronyms and ahhreviatibns abound throughout the literature on computers, and this presents a major communications barrier to any newcomer to the field. Persons whoinhahit computing centers speak a jargon all their own. Some of them even understand it! The rest of us need at least a minimal knowledge of what a computer is and how it operates before we can converse intelligibly with such persons, and converse we must if we want to find out how to get the neat computer-based nackaee that Professor Smith demonstrated at the ACS Meeting to work on our machine. The next several sections briefly present definitions and facts about computers that we, the authors, have found useful to know in the process of writing and using computer-based materials and of exchanging them with chemists at other institutions. If you want more details on computers and computer jargon, consult references (I)-(7) in the bibliography.
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Computer Fundamentals In this series of articles the word "computer" refers to a digital computer, one that performs its tasks using discrete, discontinuous signals. Analog computers, which use a continuously transformable physical quantity as an analog representation of each variable, are much less commonly used in chemistrv instruction. Althoueh in nrinci~lea dieital computer n d d use any numher of discrete signal levels, modern machines use onlv two. This is vossihle because mans- phviical .. situations having two discregstates, such as the presence or absence of an electric current or a potential difference, and the orientation of a magnetic field in one direction or its opposite, can he realized and detected quickly, inexpensively, and reliably. Any physical situation of this type can he taken to represent one or the other of the binary digits (hits) 1or 0. Consequently, data and information are represented within a computer in terms of binary numbers. The most elementary component of any digital computer is the register, aphysical device that can store some value. A Volume 56, Number 3, March 1979 1 141
L- - - - - - - - - - - - - - - - - - - - Figure 1. An example of a register. The number 10012 = by sening the switches by hand.
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has been stored
single wire might serve as a register, storing the value 1so long as current is flowine and the value 0 when the current is off. A more complex example of a register is shown in Figure 1 where the value 10012 = 910 has been stored using switches that can he manipulated by hand. (The subscripts 2 and 10 indicate binary and decimal numbers, respectively). Since this register contains four binary digits, it can store any integer 1. In a from 0 up to and including 15, that is, from 0 to 2" computer registers are made up of circuits known as flip-flops. Data stored in a register can he transformed in a numher of wavs and onerations involving two registers can he performed. For exampie, a register can bk cleareh (reset to allzeros), the ones comolement of a register can he taken (every 1changed to 0 and kvery 0 to I), the contents of one register can be transferred to another register, or the contents of one register can he added to or subtracted from the contents of another. Such re&,er operations are performed by digital logic circuits of the type described in references (I) and (8). Its ability to perform register operations makes the computer an all-purpose prohlem-solving machine. Turing and Post (9) proved independently in 1936 that the proper seauence of reeister onerations can solve any computational or information-processing problem. The only condition required is that an algorithm exists. An algorithm is an abstract statement of a finite numher of distinct steps that provide a solution. Algorithms can be made concrete in the form of computer programs. A program specifies which operations are to be performed on what data to solve the problem. Some of these operations may he conditional. That is, they are performed only if the data meet a certain condition. If not, an alternative operation is performed. Also, acomputer program itself can he read and stored by the computer as a sequence of binarv numbers. Each number is a code for a particular operation. Thus when one program has been carried out it can
he replaced easily by another. Conditional operations and stored programs are important aspects of all modern general purpose computers (10). T o solve orohlems and to communicate with the outside world, a computer needs the five types of components shown schematically in Figure 2. The input and output units allow programs and data to enter the machine and results to exit. The memory stores programs, data, and intermediate results. Register operations are performed in the arithmetic-logic unit (ALU), and the overall operation of the computer is overseen hv the control unit. The . nhvsical . devices that ~ e r f o r mthe input, output, storage, arithmetic-logic, and control functions are called the hardware. while the collection of programs available to the computer is referred to as the software. The control component has a fundamental repertoire of instructioru that it can carry out. Each instruction corresponds to one of the binary program codes. An instruction initiates some operation in the ALU or causes the transfer of a register value to or from the memory, output, or input romnonents. The control unit and the ALU usuallv occupy - ~-~~ the same cabinet or circuit hoard, and together th& are ; ;ferred to as the central processing unit (CPU) of the computer. (A portion of the circuitry for the CPU of the DECsystem-10 computer a t Eastern Michigan University is shown in Figure 3.) Central processing units differ in the numher and tvoes of instructions that are available, in the speed a t which iiHtructions can be executed (carried out), in the number of hits per register, and even in overall physical size. A microprocessor is a CPU in which all circuits are integrated onto a silicon chip on the order of 5-mm square. This permits a complete microcomputer to be built on a circuit board no larger than this page and results in costs as low as $100 for a device having rudimentary inputloutput and a small memory. Minicomputers generally have larger registers, instruction sets that are more extensive and efficient, and more memory. Of course they cost more, too. Mainframe computers of the 2~~~
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unit U L U J
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Central processing
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unit iCPW I I I 1 ------------J
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Figure 2. Simplified schematic diagram of the five fundamental types of companems in a computer system.
142 / Journal of ChemicalEducation
Figure 3, The central processing u n ~Iit i r u ) or the uttisystem-IU at taster" Michigan University with the cover removed to show internal wiring.
type found in large businesses, universities, and research laboratories are the most complicated and expensive of all. Cost and complexity must be balanced against greater convenience and meed of operation. T o take a very simple example, mu~ti~iication can be done by repeated addition, nrovided the software specifiesand counts all the adding.steps. 'On the other hand special multiplier circuits, that is, more complex hardware, can do the same operation in many fewer program stcps and nwch less time. Variations amung CPU's result in significant wriarions in computrrarcl~rrvcturr,that is, in the overall organization and interconnection of computer components. The main storage or memory of a computer may be thought of as a large collection of registers, usually of equal size, each of which is referred to as a word, storage cell, or memory location and is identified by a unique binary numher called an address. The time required for the CPU to specify the address or location of a memory register and retrieve the contents is called the access time. The access time for one memory location is essentiallv the same as for anv other. and on a stateof-the-art memo& it is usually in theiange i f 10-100 ns. The number of words and the word size (the number of hits that can he stored in a given word and transferred by a single memorv access) varv from one computer to another. Both must bk specified if ;ou want to knob how much memory is availahle or needed. For example, a program that requires 8K 36-bit words could not he run on a computer whose availahle main storage consists of 16K 16-hit words. The program takes up 8192 X 36 = 294,912 hits while the computer has availahle only 16,384 X 16 = 262,144 bits of storage. (Although the K in 8K is derived from the metric prefix kilo-, it is generally convenient for the number of words in a memoryto he an exact power of two. Hence K refers to 1024, the power of two that is closest to 1000). In order to run the program in question, the user of the 16K machine would have to modify the (or the wav the . oromam stores its data) so that fewer .oromam .. .. memury w
