PRACTICAL ASPECTS QF PROGRAMME WRITING D. R. Hogg, B.Sc., Ph.D. Dept of Chemistry, The University, Aberdeen At39 2UE 29 . . .. .. .. .. .. .. . . 27 . . .. 39 Some aspects of programming in physical chemistry Choice of topic, 39 The objectives, background knowledge and testing of the pro- grammes, 41 Writing the programme, 42 . . * . * . Acknowledgements References and R. B. Moyes, B.Sc., Ph.D.,A.R.I.C. Dept of Chemistry, The University, Hull HU6 7RX Introduction The technique of programming . . .. .. .. .. . . Preliminary work, 29 Writing the programme, 32 Revision and rewriting, 38 INTRODUCTION . . . . . . . . * . .. .. . . . . .. 43 .. .. 43 Programmed learning is a teaching technique which has developed over the last decade into an important tool for education and training.It has found widespread use in such diverse fields as management training, systematic fault finding in electronic equipment, instruction in safety procedure for miners and in neuroanatomy. Its use is not however restricted to scientific and technological subjects ; a delightful programmed book1 has been written on the Battle of Waterloo and, in the same series,2 programmes have been published on the English sonnet, German grammar and Latin. In principle it appears that any material that has to be learnt can be taught by the pro- grammed technique. Probably the most obvious characteristics of a teaching programme are that the material is presented in a series of definite steps called ‘frames’ and that some form of active ‘response’ is required of the learner.In the ‘linear’ programme developed by Skinner3 each frame provides informat ion and poses a question or requires some other activity to complete the frame. The reader answers the question or completes the frame with the appropriate response before moving on to the next frame. The correct answer or response is supplied with this next frame so that immediate confirmation is given of the successful completion of the previous step. This is by far the most common type of programme and most programmed books, for example Skinner’s 0wn,4 are written in this way. 27 Hogg and Moyes The linear programme illustrates many of the essential properties of programmed material. The subject matter of the programme is presented in a carefully arranged series of steps of appropriate size by which the student proceeds in order to acquire the knowledge or skills that the programme is designed to teach.Active learning is maintained and comprehension is tested at each step by requiring the student to respond to each frame. In addition to ensuring that a given point has been understood before new material is introduced, the immediate provision of the correct answer was held3 to ‘reinforce’ the correct response, that is to increase the efficiency of the learning process, More recent work5 however has tended to cast doubt on the overriding importance of this effect. A low error rate in these responses is required so that the student can be made to feel that satisfactory progress is being maintained and the author be assured that he is communicating adequately with the student through the medium of the programme.In the linear programme, as with all programmed material, the student is able to learn at his own pace. In a linear programme all students follow the same path through the pro- gramme and no variation is allowed in the case of wrong answers. The alternative is the ‘branched’ programme and in this case there are many different paths through the programme. Several answers are provided to the question in each frame and the student chooses the answer he considers to be correct. In order to progress through the programme the student must choose the correct answer. If he chooses an incorrect answer he may be given more information and asked to choose again, be returned to an earlier frame, or be required to work through an alternative series of frames.In this way he is directed to learn material which, by his error, he has shown that he has not fully understood. Branched programmes can be produced in the form of a ‘scrambled book’, in which the reader does not progress from page one to page two, but only through those pages which are needed for him to understand the material to be learnt. Teaching machines generally use branched programmes. The programme is usually produced as a film-strip and each frame is projected on to a small screen. At the end of each frame the student is directed to press one of the buttons according to the answer chosen.This produces a fast film movement and the next frame the student requires is projected on the screen. Branched programmes are considered to favour the brighter pupil who does not have to waste time with the simpler steps, but machines are expensive and the programmes are more difficult to produce when compared with linear programmes. A more detailed account of programmed learning is to be found in the recent book by Kay, Dodd and Sime.6 An article on programmed learning in chemistry appeared in the first volume of Education in Chemistry7a and since then several further articles have appeared.7b Over the same period only 17 programmed books were reviewed in this magazines and although 80 titles are listed in Programmes in Printg many of these duplicate each other, or are available only with particu- lar teaching machines.These programmes cover a wide range of courses, some aimed at 0-level, others at undergraduate level. Some were written for the American college student and are not very suitable for British courses. R.I.C. Reviews 28 It is for this latter reason that the search has been limited to British sources. When all these books are examined, it is seen that the task of producing programmed material covering even the essentials of chemistry taught in the schools and at higher levels, has hardly been tackled. In 1966 the Royal Institute of Chemistry organized a scheme for the circula- tion of programmes at all levels of chemistry amongst interested teachers.It was hoped that this scheme would encourage the production of more programmes. The response has been disappointing and it was felt that some notes on the practical aspects of programme writing might be helpful. These were produced and distributed to the participants in the scheme. The res- ponse was generally favourable and the remainder of this review is based on a revision of these notes. It is hoped that they will stimulate an interest in programmed learning and programme writing in a wider audience. Programme writing, like all teaching-learning processes involves com- munication between the teacher, in this case the programme writer, and the pupil. There are of course certain basic principles10 which must be borne in mind but, within these limitations, the preparation of a programme and the style of presentation reflects to a large extent the preferences, personality and prejudices of the author.In this case it was considered desirable to present more than one approach to the subject. At the risk of some repetition, it is hoped that the necessary minimum of dogma has been introduced and the very personal nature of programme writing emphasized. THE TECHNIQUE OF PROGRAMMING D. R. H O W There are three main steps in writing a programme: the preliminary work, the writing of the programme and the testing, consequent revision and re- writing of the programme. It can be seen from these steps that writing a programme is in many ways analogous to preparing a new lesson or lecture.Programme writing is undoubtedly more time consuming, but the difference in the amount of time involved is not really so disproportionately large that it effectively prevents most teachers and lecturers from experimenting with the technique. Although this section concentrates on linear programmes, and the examples are chosen largely from the field of organic chemistry, much of the material also applies to branched programmes, and the examples could have been chosen equally well from other fields of chemistry. Preliminary work The obvious first step is the choice of a topic. It is useful to ask oneself three questions about this: Must the student be able to understand and apply this information in order to progress with the subject as a whole? At this stage in their development do students, in general, find this topic difficult? and Can the topic be sub-divided into smaller topics, each of which would give a viable programme ? The answers to the first two questions will indicate the usefulness of a programme on this topic, while the last question guards against tackling a project which may prove to be too ambitious.A large topic is probably best covered by a series of programmes which are prepared separately, rather than Hogg and Moyes 29 as a whole. Attempting too large a topic is probably one of the most common mistakes of aspiring programme writers. The next step is to decide what knowledge or skills the student should possess after working through the programme.This is probably best done by setting a series of questions that students would be expected to answer after completing the programme. It is desirable to set several questions on each of the final points in the topic, and also to set questions on any points which must be established in order to reach the final points in the topic. In setting these questions it is important to bear in mind that their purpose is to test comprehension and not necessarily to grade the students, although naturally some students will always do better than others. One of the most important properties of this set of questions is that it begins to divide the topic into objectives which are sufficiently small and precise to be useful. For a topic such as Boyle’s law the questions would probably encompass the statement of the law, the equation, a numerical problem the solution of which depends upon the application of the equation, a numerical problem which illustrates the experimental verification of Boyle’s law, possibly the identification of a statement as Boyle’s law and so on.If the ability to answer these questions represents the knowledge or skills that the student should possess after completing the programme then they collectively are the educa- tional objectives of the programme. It is much more useful when writing the programme to have as objectives ‘the ability to state and recognize Boyle’s law; the ability to express Boyle’s law as an equation; the ability, given the initial and final pressures and the initial volume, to calculate the final volume at the same temperature; the ability to solve a given problem involving pressures and volumes by applying Boyle’s law’, than an objective such as ‘to give a thorough understanding of Boyle’s law and its applications’.The latter will have to be converted, con- sciously, or subconsciously, into something resembling the former, before any real progress can be made with writing the programme. At this stage it is strongly recommended that the objectives of the pro- gramme be written down. It is also beneficial to revise any sentence or phrase in the objectives which contains one or more of the words, comprehend, knowledge, know, understand, understanding and appreciate. Their meaning is too dependent on the academic level of the programme for them to be useful in this context.Magerll suggests that when preparing objectives, one should ask the questions What will the student be doing when he is demonstrating proficiency? Under what conditions will this behaviour occur ? The answer to the first question must specify definite actions, e.g. stating Boyle’s law, writing P1V1 = P2V2. The second question refers to the informa- tion or equipment which must be given or be available in order to produce the required action. Having chosen a topic, decided precisely what is to be taught in the pro- gramme and produced a series of questions suitable for a terminal test (not necessarily in that order), the next step is to consider how much relevant knowledge the student can be assumed to possess.For a teacher writing a programme for his own students this does not pose too much of a problem, but if the programme is to be used by a wider audience then it is necessary to R. I. C. Reviews 30 state the knowledge which is assumed so that other teachers may decide whether it is suitable for their own classes. If too little previous knowledge is assumed the programme moves too slowly for the pupil and he tends to become bored. Boredom induces carelessness and he begins to make mistakes in his responses. If too much knowledge has been assumed then at some point the programme will move too rapidly for the student and again he will make mistakes. Although the assumption of too much knowledge and the assumption of too little knowledge both lead to mistakes in the responses, the latter is generally identified more readily as the mistakes are concentrated over a smaller section of the programme and involve a much higher percentage of the students.As the assumption of too much knowledge can be corrected by adding extra information, whereas the alternative error requires a much more extensive revision of the programme, it is preferable, in cases of doubt, to err on the side of assuming too much previous knowledge. In this way, after the pro- gramme has been revised, the students are given all the information they require and not all the information the programmer thinks they require. There is another way around this difficulty.If the amount of information is small and is not sufficiently familiar to be recalled by the student, then the problem can sometimes be resolved by incorporating the information in the frame (see later) or in a previous frame. Although this is not considered to be desirable by some programmer^,^^ in the opinion of the author the incorpora- tion of additional information is justified under the circumstances described or when it would obviously stimulate further interest. The tactic should not be used too frequently and it must be remembered that this information cannot be assumed to be known at a later stage of the programme. Having defined the initial and final levels of knowledge, the programme itself can be planned. Generally it is difficult, and by no means necessary, to avoid planning sections of the programme before this stage.It is imperative that the subject matter be developed in a logical orderly manner. A useful method is to use a paper with a line down the centre. On one side the points which are to be made are written in what appears to be the most appropriate order, leaving plenty of space; on the other side the type of frame considered suitable for this section of the subject matter is jotted down together with any ideas for actual frames which immediately come to mind and the approximate number of frames required to cover this point. These points are rearranged as required and the jottings amended and increased. This method is probably most useful when the logical order for the subject matter is fairly obvious or has been roughly determined.It is sometimes advantageous to produce a flowsheet for the development of the subject matter or to write on cards which can be rearranged more easily. The approxi- mate number of frames for each point is considered to ensure that a balance is maintained in the programme as a whole and that the programme will be approximately the required length. Naturally some experience is required before a confident estimate can be made of the average time taken by students to complete a programme. As a rough guide a collection of ‘long’ frames will take 2-3 min each, whereas if the programme consists of ‘very short’ frames the average falls to 20-30s per frame. In the experience of the author a 31 Hogg and Moyes 3 mixture of short and long frames seems to give an average of approximately 1 min/frame for university students.12 One of the much publicized advantages of programmed learning is that the student can work at his own pace, and there is invariably a spread from approximately one half of the average time to twice the average time.The average length of time required to complete a programme is obviously impor- tant if the programme is to be used within a lesson, where the timetable requirements are rigid, but the length is also important when the programme is intended for private study. Apart from the limitations imposed by the amount of time the student has available and the obvious proviso that the time required to complete the programme should not be disproportionate with respect to the importance of the subject matter, programmed learning is an active method of learning requiring a high degree of concentration and students tend to tire quite rapidly.It is doubtful whether a student can concentrate efficiently on a programme for more than 30-40 min and if the time taken to complete the programme considerably exceeds this limit then the content of the programme should be organized to provide a break after a suitable period of time. In this portion of the preparation the aim is to produce a set of notes or a plan which will assist in writing the programme. The aim is not to produce a written account of the topic which can be sliced up into convenient pieces, in order to provide small steps into which ‘active participation’ can be injected by the removal of one or more words.The programme should be written as a connected series of frames for each point, using the plan or notes merely as a guide: in the opinion of the author it is not desirable to give these notes any additional function. As in other forms of teaching the recall of certain types of information, or the practice of certain skills, e.g. recognition, requires frequent repetition in order that the material or skill be thoroughly learnt. There must be a reason- able time interval between the requests for repetition of the information or skill, to ensure that true retention has occurred and not brief temporary retention. In the final check through the plan it is worthwhile to look for situations in which earlier material can be repeated without ruining the logical development of the programme.The places at which definite revision loops can be inserted should also be indicated on the plan. When the objectives of the programme have been defined, the final test written, the amount of knowledge which can be assumed has been decided and a plan for the programme drawn up, then the actual writing of the programme can commence. Writing the programme In writing a programme the information is presented to the pupil in a series of small steps. This leaves unanswered the important question, How small must these steps be? A possible answer is that the step must be small enough to be negotiated without undue difficulty by the vast majority of the students for whom the programme is intended and yet pose a satisfactory challenge to them.From this it follows that the absolute size of step should increase as the average ability of the students increases. The size of step refers to the R.I.C. Reviews 32 degree of difficulty in comprehension not, of course, to the number of words used in the step. Each small piece of information presented to the student is referred to as a frame and in each frame the student must answer a question or make some other response. Consequently programme writing involves writing a connected series of frames requiring suitable responses. In writing frames three principles must be kept in mind. 1.The student must respond actively to each frame. This does not mean that the student must do something, however trivial, in each frame but that mentally he must process the entire frame to produce the required response. This principle is derived from the reasonable hypothesis that a student can only be assumed to have learnt the material he has been directed to read by the requirements of the response. 2. A frame must produce a minimal number of errors from the student. This principle does not require that all the students should produce the correct response but that most should. If a large number of erroneous res- ponses is produced it indicates that the frame is unsuitable either because it is ambiguous, or because the step is too large.It is not advisable to specify a minimal number and follow it rigidly. In practice there seems to be little difficulty with this point. 3. The student must be informed of the correct response immediately after completing the frame. This means that the correct response must be incor- porated& the programme adjacent to the frame, i.e. under the frame, on the back of the frame, at the side of the frame etc. A collection of correct responses at the end of the programme is not generally considered to be suitable. Within the limitations imposed by these three principles any type of frame and response may be used. Personally I consider it advantageous to use several types of frame and response in a programme as it introduces variety into the students’ work and presumably stimulates interest and reduces boredom.The second principle, minimal errors, leads to an important aspect of frame writing-methods for helping the student to produce the correct response. In this respect the orderly construction of the subject matter is probably of primary importance and gives the student a very powerful ‘prompt’ sometimes referred to as a ‘sequence prompt’. A prompt has been definedlob as ‘some- thing added to a frame to make the frame easier and which is not suficient of itself to produce a response, but depends on previous learning’. Under certain circumstancesframe l a could be called a ‘terminal frame’; that is, it contains an item which the student is expected to know after completing the pro- gramme.(Frame / a ) In a polar reaction the reacting centres are called The definition and use of the terms electrophile and nucleophile would be one of the objectives of this programme. If this is a terminal frame it should Hogg and Moyes 33 not contain a prompt and should be separated, as much as is practicable, from frames introducing this topic in order to reduce sequence prompting. Terminal frames may contain unavoidable hints arising from the grammatical structure. In frame la, for example, the response must be more than one noun, or a plural noun. If this type of hint is used intentionally it is sometimes called a ‘syntax prompt’. Frame l a can be made successively easier by the addition of prompts. First the response can be limited to two nouns, secondly the response can be further limited to two nouns one beginning with ‘n’ and the other with ‘e’, and finally the response is limited to two nouns one beginning with ‘e’ containing 12 letters in the word and the other beginning with ‘n’ containing 11 letters.This is illustrated in frames lb-ld. In a polar reaction the two reacting centres and the n (Frame Ib) In a polar reaction the two reacting centres are called the ~ _ _ . _ and the are called the . _ _ (frame Ic) - e __ - (Frame Id) are called the In a polar reaction the two reacting centres e - - - - - - - - - - - and the El - - - - - - - - - -. Another type of prompt which is used extensively is the choice of alterna- tives, This is illustrated in frame 2 where the response is limited to one of three words.(Frame 2)13 W e found that two similar charges may remain connected by the brass con- ductor without change, but were surprised that two (equal/different/ large) charges disappeared altogether when so connected. In frames 1 and 2 prompts were used to produce single word responses. With other responses, prompts must be incorporated in less obvious ways. In frame 3 the problem of incorporating a prompt has been solved by stating a rule and giving a worked example; the student is then required to respond by completing the incomplete example. Both the rule and the example are prompts and either of them may be removed in turn. (frame 3)f4 I n any reaction between two substances one is referred to as the REAGENT and the other as the SUBSTRATE.This nomenclature i s somewhat arbitrary but the inorganic substance, the ion, or the smaller organic molecule is usually referred to as the reagent, e.g. R. I . C. Reviews 34 + + reagent C6H6 substrate HzN03 -----+ CsHsNOz + H2O I- + (CH3)zCH’ + (CH3)zCHI reagent substrate Classify the following reactants as reagents or substrates. Clz + CH2=CH2 ____P etc. This is a particularly flexible type of frame which is suitable for the introduc- tion of many chemical concepts. After the material has been introduced it is sometimes useful to vary the order of presentation. That is, instead of using the rule as a prompt for the example, an example could be used as a prompt for the rule.Frames 4a-d illustrate this approach. (Frame 40) rule and example as prompts for an incomplete example. Markownikoff’s rule states ‘the negative part of the addendum adds predomi- nantly to the carbon atom carrying the smaller number.of hydrogen atoms’. In the examples below the halogen i s the negative part of the addendum, e.g. CH3CH==CH2 + HCI -----+ CH3CHCICH3 Complete the following reaction: (CH3)zC=CHz + HCI ------+ (Frame 46) rule as a prompt for an incomplete example. The addition of hydrogen iodide to 2-methyl but- I -ene obeys Markowni koff’s law (the negative part of the addendum adds predominantly to the carbon atom carrying the smaller number of hydrogen atoms). Complete the reaction: CH~CH~C=CHZ + HI -----+ I CH3 ____ (Frame 4c) example as a prompt for an incomplete example CHsCH=CHz + HCI ---+ CX3CHCICH3 Complete the following reactions: CH3CH=C(CH3)2 + HI ---+ etc.(Frame 4d) example as a prompt for the rule. The following additions obey Markowni koff’s law: CH3CH=CHz + HI ---+ (CH3)2C=CHz + HCI ---+ (CH3)2CCICH3 CH3CHICH3 State Markownikoff’s law: Hogg and Moyes 35 This type of frame is particularly suitable for programming descriptive work. In the programme, frame 5a (rule, example, incomplete example) is separated from frame 5b (example, incomplete example) by a series of frames on the mechanism of the reaction. (frame 50)15 R' \ / / \ \ / R \ R' R - c=c R Olefins can be prepared from alkyl halides and carbonyt compounds (alde- hydes and ketones) through the agency of triphenylphosphine (Ph3P) and a strong base such as sodium ethoxide (NaOEt) or n-butyl lithium (BuLi).The overall reaction can be written R' CHBr + O=C / Ph,P, BuLi R' R Met hylenecyclohexane Methylenecyclohexane can be prepared from two al kyl halide/carbonyl compound combinations. What are these? What other reagents (names and formulae) are needed? (Frame 5b) The whole sequence can be written: Ph,P EtBr -.+ f + - Ph3P=CHCH3 P h 3 P-C H C H3 Ph3PEt Br- _+ -+ Et,C=O EtzC=CHCH3 + Ph3PO Write your reaction between isopropyl bromide and acetone in this way. In frame 5a the last response merely requires the student to copy the statement given in the rule section of the frame.The amount of learning produced by this type of response is probably very small and frames in which this is the only, or the major response tend to irritate many students. The bask objection to this type of response, a copying response, is that the step is too small. Inframe 5a the copying response is only a minor part of the res- ponse, but it could have been avoided by rewording the statement defining the response. Frame 6a is undoubtedly just a copying frame of the type which tends to occur in introductory frames using single word responses. Another method of avoiding copying frames is illustrated in frame 6b which poses a series of simple direct questions. In the opinion of this author, copying frames should not be used.R.I.C. Reviews 36 (Frame 6a) Markownikoff (1869) studied the addition of hydrogen halides t o olefins and formulated the rule 'the negative part ofthe addendum adds predominantly to the carbon atom carrying the smaller number of hydrogen atoms'. With the hydrogen halides the halogen i s the negative portion of the addendum. The rule holds satisfactorily for hydrocarbons but there are some exceptions t o the rule when it i s applied to olefinic compounds which are not hydro- carbons. Markownikoff's rule states: the part of the addendum adds predominantly t o the carbon atom carrying-the smaller number of ~ ____-__-. atoms. (Frame 6b) CI I CH3--CH=CH2 + HCI + CH3-CH-CH3 CI CHrC=CH2 + HCI ---+ CH3-4-CHs CH3 or i s it polarized in the sense H8-- CI"? Hydrogen chloride readily donates a proton, Hf.Is hydrogen chloride polarized in the sense H*+-CI*-, CH3 I - CIS+. H*+-------C18-/H8- Would you refer t o chlorine, rather than t o hydrogen, as the negative portion of the molecule? yeslno In the reactions above does the negative portion of the molecule add to the carbon carrying the smaller number of hydrogen atoms? yes/no etc. In frame 6a the student only requires to read the words 'Markownikoff formulated the rule' and the portion in italics in order to respond correctly to this frame. The remainder of the first paragraph does not have to be considered in order to produce the response and thus, with respect to this information, the frame violates the principle of active response.If the two extra points introduced in frame 6a are necessary they should have been made the subject of additional frames. Although, as previously indicated, it does not seem necessary to follow this principle rigidly, it is advisable to check each frame to remove any unintentional deviations. At each step in the programme it is necessary to pose an adequate challenge to the student. With the more able students it is difficult to create a large enough learning step using frames which require only the addition of one or more words. This difficulty is aggravated further by the principle of active responding which restricts the length of the statement for each response. In my opinion this type of frame should be avoided as much as possible and its use limited to short frames having one or two responses.It would seem desirable to vary the type of frame used in a programme as much as possible, not only because this must surely make the programme more interesting to Hogg and Moyes 37 the student, although this would be reason enough, but also because it makes programmed learning more flexible with regard to the subject matter to which it can be applied. It also makes programme writing easier and more interesting. In this section examples have been given of various types of frame and these examples may be supplemented from a survey of recently published programmes.13-15 The only limitation on the format is that the frame should give a learning step of appropriate magnitude and that it should be capable of fulfilling the three basic principles.It is also desirable that the response be closely connected with the immediate aims of the teaching. If the programme teaches a practical skill the preferred response should be a practical response. Revision and rewriting It cannot be emphasized too strongly that, however carefully a programme is prepared and written, the first version can be regarded only as a rough draft. As programmed instruction is a learning method more than a teaching method, the document produced can be regarded as a programme only after it has been used by a reasonable number of students and suitably modified in the light of their comments, incorrect responses and general performance.The problem is how to obtain this information. From the literature on programmed learning it would appear that other authors have an ample supply of students and free periods in which they can test frame sequences written on talc for back-projection, or in which they can watch small batches of students work through the original manuscript and make the necessary corrections on the spot. If, as is generally the case, these facilities are not available, then this infor- mation can be obtained by incorporating an information sheet with the programme. The information sheet used by the author requests the numbers of the frames, including terminal frames to which incorrect responses were given, the incorrect response itself, any comments on this error, general comments on the programme and the time taken to complete the programme.The students hand in these sheets after completing the programme. Inevitably not all the students hand in sheets and, of those who do, not all of them fill in the sheets conscientiously, but from 80-100 students sufficient do so to make it worthwhile. These sheets produce encouragement and humour as by- products as well as honest criticism. All the incorrect responses and other details are then entered on to a copy of the programme. The results are generally clear cut. Certain frames and certain sections are unsatisfactory, either because they are badly expressed, or because examples have been badly selected, or because too much knowledge has been assumed.These frames and sections must then be rewritten and tested again until they are satis- factory. With a very much smaller number of students it takes longer to oollect enough information for a worthwhile revision. However, the teacher in this position will obtain more information per student than his colleague with a large group, where the relationship is generally more impersonal, and should obtain sufficient information from two or three classes. Assistance in testing R. I. C. Reviews 38 programmes can in any event be arranged through the Royal Institute of Chemistry’s Education Department. SOME ASPECTS OF PROGRAMMING IN PHYSICAL CHEMISTRY R. B. MOYES In the preceding part of this review Dr Hogg covered most of the practical matters related to programme writing; here I will confine myself to some personal views.I believe that the best programmes are those that the teacher has written for his own classes and which are related to their particular problems. Programmes written by other people always seem to contain difficulties of nomenclature or approach which make them inferior to those produced by the teacher himself. Further, once a teacher has written his own programmes, amendment and correction are often easy compared with the difficulties involved in making large numbers of minor corrections to others’ programmes in order to make them compatible with existing courses. The steps in writing a programme are dealt with in more detail below. They can be summarized as: (a) choice of topic; (b) definition of the aims and objec- tives of the programme; (c) consideration of the knowledge the student brings to the programme; (d) writing a draft; (e) testing the result; (f) revising the programme. Choice of topic In my view the choice of topic is crucial.Much of the early success of pro- grammed learning can be attributed to the students’ interest in a new teaching technique. When this motivation is removed and programmes are just a part of the course many of their advantages appear to be lost. Often, in order to deal with a topic in the programmed form, the student may be asked to spend much more time on it than he would normally. An example of this is the attention paid to the nomenclature of organic compounds by some programme writers.Some of these are short pithy accounts of the subject while others go to inordinate lengths because the subject lends itself to a logical approach. Organic nomenclature is not, however, a sensible subject for a programme at university level because most competent students can grasp the principles more quickly than the time involved in working through most of the published programmes. A further reason is that the student will want to refer to the prhciples of nomenclature when in doubt, something almost impossible within the usual programme form. This latter problem is often a difficulty with programmes since they seldom contain an easy method of reference to important sections. Some teachers would maintain that nomenclature is a matter which the student learns by practice and the artificial practice of the programme is not what is wanted.What then are the criteria for choosing a topic? First it must be one that the student$nds dzficult. Secondly, it must lend itself to the programmed form, and lastly it must justify the amount of time which the student will spend on it. Perhaps this could be amplified by an example from my own experience. I have to teach physical chemistry to students of biology whose mathematical abilities are modest. Nonetheless, I believe that much of the algebra of Hogg and Moyes 39 physical chemistry can be understood by these students and is worthwhile so long as each step is carefully explained. I feel that chemical lessons resulting from the mathematical logic are useful to the student and cannot be learned without working through the algebra.So my first programme deals with the commonly found algebra by which formulae for rate equations of various orders can be obtained, and their use in determining the order of reaction. The second programme shows how the steady-state approximation can be used to explain empirically-found rate equations. I think that these programmes fulfil the requirements given for choosing a programme. It is a topic found difficult by most of these students; it readily lends itself to the programmed form and the work involved is no greater than that normally expended by students on this subject. Example from kinetics I The time for half the reactant t o decompose will be for x = for x = a12 14 In the equation, kt = In a/a - x , so kt, = kt,= Inala- fa=In2= 15 16 so t, = 17 How does t, vary with initial concentration? 18 This constitutes another test of first-order kinetics. We look for a half-life time which is - - - - - - - - - - - of the initial concentration.In what units can k (the rate constant for a f i r s t order reaction) be expres- 19 sed? - _ _ _ _ ~ _ _ _ _ _ t, = 0.69/k i s independent of initial con- centration; ‘a’ does not appear in independent l a Time-1. As k = - In ___ the t a - x 2.30 x 0.3010 = 0.69 t, the formula. I units are - x a pure number. time The units of k must, then, be time-1 (i.e. s-1, min-1, years-”). You will remember logarithms are dimensionless.R.Z. C. Reviews 40 20 In what field do we find half-life times of years? Rad i oact i ve d is i n teg r a t i o n s. 21 This is a rate equation again. For example, if t, for radium i s 1590 years, what i s the value of k? - Example from kinetics / I ( i ) CH3CHO .-> CH3 + CHO ( i i ) CH3 + CH3CHO .kzc CH4 + CO + CH3 ( i i i ) 2CH3 ~-+ k3 k i C2Hs Then d[CH3]/dt = __. _ _ _ _ 12 Suppose the mechanism of the reaction is 13 So, by making the steady state approximation, we say d[CHs]/dt = 0 or rate of formation of methyl radicals = rate of loss of methyl radicals, d[CH3]/dt = 0 and we can calculate concentration of methyl radicals [CHs] a t this stage = 14 Now, rate of formation of methane is d[CHa]/dt = 15 Substitute for [CH3].d[CH4]/dt == k2(kl/k3)a[CH3CHO]g So this mechanism can explain why the reaction is three halves order in acetaldehyde. Reaction ( i ) produces CH3, reac- tion ( i i i ) destroys it, reaction ( i i ) has no effect on [CH3] as it is produced and destroyed, so d[CHsJ/dt = kl[CH&HO] - k3[CH3]2 [CH3] = (kl/k3)$[CH3CHO]a (nb .\/x = x i ) only reaction ( i i ) makes CH4 so d [ C H 4]/d t = kz[C H3C H 01 [ C H3] ___--__I_____ _____. The objectives, background knowledge, and testing of the programmes The objective of the first programme is to allow students successfully to complete the logical steps leading to formulae which will be of use to them, Hogg and Moyes 41 and of the second to afford them practice in applying a simple approximation which leads to interesting conclusions.Having completed these programmes, a student should be able to obtain the formulae mentioned in the first pro- gramme and to apply the steady-state approximation to simple reactions. Unlike Dr Hogg, I do not apply specific tests to gauge the success of the programmes but instead try to estimate the effect they have on the answers given in the usual class examinations. This is because I attempt to integrate programmes with the rest of the course in physical chemistry, of which they are only a small part, and I think that it is in this respect (assistance with the teaching of difficult areas of the subject as a whole) that they must be judged.In the development of programmes tests of their effectiveness are necessary, along with the answers to the frames. These make the revision of the pro- gramme possible but, in my view, give the programme unnecessary emphasis when it is used routinely. Again, because they are integrated parts of the course, I know what know- ledge students will have when they are given these programmes to work through. Specifically, they will have attended lectures in which most of the content of the first programme will have been discussed and the principles of the methods used in the second programme. For this reason, in the strictest sense, these programmes are useless to other teachers except where they follow lectures of the same kind. These programmes have been revised three times but there are still some errors which need correction.I have long regretted that I chose the HZ-Brz system as an example of a complicated chain reaction because it contains possibly too much algebra and too little chemistry. For this and other reasons, I do not consider these programmes to be ‘finished’. There is always a temptation to tinker with them but this may itself be an advantage as it presents one with the opportunity to bring material up to date. After all, how often does a good teacher teach exactly the same lesson every year? Writing the programme Far too much has been written on the topic of writing programmes, and far too much of it is still controversial for me to hazard more than a personal opinion.I feel most students are used to their teacher’s style and when written down it will still be familiar. Some obvious errors are worth remarking on, although personal preferences are difficult to forecast. In some programmes I have noticed a tendency to write long frames containing too much informa- tion and requiring too little response on the part of the student. It should be remembered that programmes are more than books with the occasional word .missing. Some authors spend too much time on definitions which are principally concerned with the technical use of words, for, while it is important to define these terms, they often occupy a disproportionately long and boring section of the programme and reduce the student’s concentration on the important work which follows it.The next comment, that concerning the minimal number of errors, involves R.I.C. Reviews 42 the achievement of a difficult balance between boring the student and con- fusing him, and it is here that the experience of the teacher in relation to his class is most valuable. Teachers attempting to write programmes should not be too anxious to avoid difficult steps since these encourage the brighter student who can sometimes be assisted by a hint written below the original quest ion. My final comment involves the careful placing of the correct response. Again there must be a judicious choice between a clear invitation to cheat and hiding the answer so far away that a frustrating search is required. For this reason I cannot recommend the scrambled book technique for dealing with branching programmes.My experience with the programmes I have written is that those students who cannot be bothered to work through the frames properly are unlikely to want to read the programme at all. Most students are quite willing to use the programme in the way intended and it seems pointless to include anti-cheating devices for the aberrant few. In any case there seems to be some evidence that simply reading the programme, answers and all, is still beneficial. In conclusion it must be said that programming is simply another method of teaching. It does not replace anything or anybody, but merely makes the task of learning simpler for some students. It is regrettable that the technique has been advertised to such an extent that unsuitable programmes which are readily available may be misused by students for whom they were not in- tended.It is for this reason that I repeat my belief that the teacher must write his own programmes for his own courses. ACKNOWLEDGMENTS The examples in frames 2, 3, 5a and 5b taken, respectively, from Ionic theory by R. B. Dunn, Electronic efjrects and their applications by D. R. Hogg, and Olefins and acetylenes by F. D. Gunstone are reproduced by permission of the English Universities Press. REFERENCES P. Thornhill, The Waterloo campaign. London : Methuen, 1965. Methuen’s Clearway Programmed Books. B. F. Skinner, ‘Teaching Machines’, Scient. Am., 1961, November, 90. J. G. Holland and B. F. Skinner, The anaZysis of behaviour. London: McGraw-Hill, 1961. (a) S. M. Markle, Good frames and bad, 21, 249. London: Wiley, 1964; (b) W. A. Hershberger and D. F. Terry, J. educ. Psychol., 1965, 56, 22; S. C. Lublin, ibid., 1965, 56, 295. H. Kay, B. Dodd and M. Sime, Teaching machines and programmed instruction. Harmondsworth: Penguin, 1968. (a) F. D. Gunstone and R. B. Moyes, Educ. Chem., 1964, 1, 189; (b) D. E. Hoare and G. R. Inglis, ibid., 1965,2,32; D. R. Hogg and H. P. R. Hodge, New Educ., 1965,l (12), 30; D. R. Hogg in Aspects of educational technology, ed. D. Unwin and J. Leedham. London: Methuen, 1967; R. B. Moyes, Educ. Chem., 1966, 3, 182; P. S. Adey, ibid., 1966, 3, 302; ibid., 1967, 4, 141 ; N. A. Coats, ibid., 1969,6,21; M. Collard, J. Griffith, H. Liddy, V. Shuk, and E. S. Swinbourne, ibid., 1969, 6, 130; G. M. Seddon, Chem. Brit., 1967,3, 160; (c) W. K. Richmond, Educ. Chem., 1968, 5, 109. Educ. Chem., 1964,1,163; 1966,3,44, 145; 1967,4,101,304; 1968,5,38,44, 129, 135, 177, 179; 1969,6, 30, 71, 189, 193, 194, 235. Hogg and Moyes 43 Learning and Educational Technology, 1969. 10 (a) P. Pipe, Practicalprogramming. New York: Holt, Rinehart and Winston, 1966; 9 P. Cavanagh and C. Jones, Yearbook of educational and instructional technology 1969-1970, incorporating Programmes in print. London : National Assn for Programmed (b) S. M. Markle, Good frames and bad. London: Wiley, 1964. 1969. 11 R. F. Mager, Preparing objectives for programmed instruction. San Francisco : Fearon, 1961. 12 In some very limited tests students from Further Education Colleges took an average of a little less than 1.5 min per frame. The error rate was similar to that of university students. 13 R. B. Dunn, Ionic theory, 13. London: English Univ. Press, 1965. 14 D. R. Hogg, Electronic efsects and their applications, 25. London: English Univ. Press, 15 F. D. Gunstone, Olefns and acetylenes, 22. London: English Univ. Press, 1966. 44 R.Z.C. Reviews