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108fea48 KD |
1 | .\" @(#)p2 6.1 (Berkeley) %G% |
2 | .\" | |
3 | .NH | |
4 | Educational Assumptions and Design. | |
5 | .PP | |
6 | First, the way to teach people how to do something | |
7 | is to have them do it. Scripts should | |
8 | not contain long pieces of explanation; they should | |
9 | instead frequently ask the student to do some task. | |
10 | So teaching is always by example: the typical | |
11 | script fragment shows a small example of some | |
12 | technique and then asks the | |
13 | user to either repeat that example or | |
14 | produce a variation on it. | |
15 | All are intended to be easy enough that most students will get most questions | |
16 | right, reinforcing the desired behavior. | |
17 | .PP | |
18 | Most lessons fall into one of three types. | |
19 | The simplest presents a lesson and asks for a yes or no | |
20 | answer to a question. | |
21 | The student is given a chance to experiment before replying. | |
22 | The script checks for the correct reply. | |
23 | Problems of this form are sparingly used. | |
24 | .PP | |
25 | The second type asks for a word or number as an answer. | |
26 | For example a lesson on files might say | |
27 | .IP | |
28 | .I | |
29 | How many files are there in the current directory? | |
30 | Type ``answer N'', where N is the number of files. | |
31 | .R | |
32 | .LP | |
33 | The student is expected to respond (perhaps after experimenting) with | |
34 | .LP | |
35 | .I | |
36 | answer 17 | |
37 | .R | |
38 | .LP | |
39 | or whatever. | |
40 | Surprisingly often, however, the idea of a substitutable argument | |
41 | (i.e., replacing | |
42 | .I | |
43 | N | |
44 | .R | |
45 | by | |
46 | 17) | |
47 | is difficult for non-programmer students, | |
48 | so the first few such lessons need real care. | |
49 | .PP | |
50 | The third type of lesson is open-ended \(em | |
51 | a task is set for the student, | |
52 | appropriate parts of the input or output are monitored, | |
53 | and the student types | |
54 | .ul | |
55 | ready | |
56 | when the task is done. | |
57 | Figure 1 shows a sample dialog that illustrates the last of these, using two | |
58 | lessons about the | |
59 | .I cat | |
60 | (concatenate, i.e., print) command taken | |
61 | from early in the script that teaches | |
62 | file handling. | |
63 | Most | |
64 | .I learn | |
65 | lessons are of this form. | |
66 | .KF | |
67 | .TS | |
68 | box, center; | |
69 | c. | |
70 | T{ | |
71 | Figure 1: Sample dialog from basic files script | |
72 | .sp | |
73 | (Student responses | |
74 | in italics; `$' is the prompt) | |
75 | .nf | |
76 | .sp | |
77 | A file can be printed on your terminal | |
78 | by using the "cat" command. Just say | |
79 | "cat file" where "file" is the file name. | |
80 | For example, there is a file named | |
81 | "food" in this directory. List it | |
82 | by saying "cat food"; then type "ready". | |
83 | $ \fIcat food\fR | |
84 | this is the file | |
85 | named food. | |
86 | $ \fIready\fR | |
87 | ||
88 | Good. Lesson 3.3a (1) | |
89 | ||
90 | Of course, you can print any file with "cat". | |
91 | In particular, it is common to first use | |
92 | "ls" to find the name of a file and then "cat" | |
93 | to print it. Note the difference between | |
94 | "ls", which tells you the name of the file, | |
95 | and "cat", which tells you the contents. | |
96 | One file in the current directory is named for | |
97 | a President. Print the file, then type "ready". | |
98 | $ \fIcat President\fR | |
99 | cat: can't open President | |
100 | $ \fIready\fR | |
101 | ||
102 | Sorry, that's not right. Do you want to try again? \fIyes\fR | |
103 | Try the problem again. | |
104 | $ \fIls\fR | |
105 | \&.ocopy | |
106 | X1 | |
107 | roosevelt | |
108 | $ \fIcat roosevelt\fR | |
109 | this file is named roosevelt | |
110 | and contains three lines of | |
111 | text. | |
112 | $ \fIready\fR | |
113 | ||
114 | Good. Lesson 3.3b (0) | |
115 | ||
116 | The "cat" command can also print several files | |
117 | at once. In fact, it is named "cat" as an abbreviation | |
118 | for "concatenate".... | |
119 | .fi | |
120 | T} | |
121 | .TE | |
122 | .sp | |
123 | .KE | |
124 | .PP | |
125 | After each correct response the computer congratulates | |
126 | the student and indicates the lesson number that | |
127 | has just been completed, permitting the student | |
128 | to restart the script after that lesson. | |
129 | If the answer is wrong, the student | |
130 | is offered a chance to repeat the lesson. | |
131 | The ``speed'' rating of the student (explained in | |
132 | section 5) is given after the lesson number when the lesson is completed successfully; it is | |
133 | printed only for the aid of script authors checking | |
134 | out possible errors in the lessons. | |
135 | .br | |
136 | .PP | |
137 | It is assumed that there is no foolproof way | |
138 | to determine if the student truly ``understands'' | |
139 | what he or she is doing; | |
140 | accordingly, | |
141 | the current | |
142 | .I | |
143 | learn | |
144 | .R | |
145 | scripts | |
146 | only measure performance, not comprehension. | |
147 | If the student can perform a given task, that is deemed to be ``learning.'' | |
148 | .[ | |
149 | skinner teaching 1961 | |
150 | .] | |
151 | .PP | |
152 | The main point of using the computer is that what the student | |
153 | does is checked for correctness immediately. | |
154 | Unlike many CAI scripts, however, these scripts provide | |
155 | few facilities for dealing with wrong answers. | |
156 | In practice, if most of the answers are not right the script is | |
157 | a failure; the universal solution to student error is to provide | |
158 | a new, easier script. | |
159 | Anticipating possible wrong answers is an endless job, and it is really | |
160 | easier as well as better to provide a simpler script. | |
161 | .PP | |
162 | Along with this goes the assumption that | |
163 | anything can be taught to anybody if it can | |
164 | be broken into sufficiently small pieces. Anything | |
165 | not absorbed in a single chunk is just subdivided. | |
166 | .PP | |
167 | To avoid boring the faster students, | |
168 | however, | |
169 | an effort is made in the files and editor scripts to provide | |
170 | three tracks of different difficulty. | |
171 | The fastest sequence of lessons | |
172 | is aimed at roughly the bulk and speed of a typical tutorial | |
173 | manual and should be adequate for review and for | |
174 | well-prepared students. | |
175 | The next track is intended for most users and is roughly | |
176 | twice as long. Typically, for example, the fast track | |
177 | might present an idea and ask for a variation on the | |
178 | example shown; the normal track will first | |
179 | ask the student to repeat the example that was shown | |
180 | before attempting a variation. | |
181 | The third and slowest track, which is often | |
182 | three or four times the length of the fast track, | |
183 | is intended to be adequate for anyone. | |
184 | (The lessons of Figure 1 are from the third track.) | |
185 | The multiple tracks also mean that a student repeating a course is unlikely | |
186 | to hit the same series of lessons; this makes it profitable for a shaky | |
187 | user to back up and try again, and many students have done so. | |
188 | .PP | |
189 | The tracks are not completely distinct, however. | |
190 | Depending on the number of correct answers the student has given for the | |
191 | last few lessons, the program may switch tracks. | |
192 | The driver is actually capable of following | |
193 | an arbitrary directed graph of lesson sequences, as discussed in section 5. | |
194 | Some more structured arrangement, however, is used in all current scripts | |
195 | to aid the script writer in organizing the material into lessons. | |
196 | It is sufficiently difficult | |
197 | to write lessons | |
198 | that the three-track theory | |
199 | is not followed very closely | |
200 | except in | |
201 | the files and editor scripts. | |
202 | Accordingly, | |
203 | in some cases, the fast track is produced merely by skipping | |
204 | lessons from the slower track. | |
205 | In others, there is essentially only one track. | |
206 | .PP | |
207 | The main reason for using the | |
208 | .I | |
209 | learn | |
210 | .R | |
211 | program rather than | |
212 | simply writing the same material as a workbook | |
213 | is not the selection of tracks, but | |
214 | actual hands-on experience. | |
215 | Learning by doing | |
216 | is much more effective | |
217 | than pencil and paper exercises. | |
218 | .PP | |
219 | .I Learn | |
220 | also provides a mechanical check on performance. | |
221 | The first version in fact would not let | |
222 | the student proceed unless it | |
223 | received correct answers to the questions | |
224 | it set and it would not tell a student the right answer. | |
225 | This somewhat Draconian approach has been moderated | |
226 | in version 2. | |
227 | Lessons are sometimes badly worded or even just plain wrong; | |
228 | in such cases, | |
229 | the student has no recourse. | |
230 | But if a student is simply unable to complete one lesson, | |
231 | that should not prevent access to the rest. | |
232 | Accordingly, the current version of | |
233 | .I learn | |
234 | allows the student to skip | |
235 | a lesson that he cannot pass; | |
236 | a ``no'' answer to the ``Do you want to try again?'' | |
237 | question in Figure 1 will pass to the next lesson. | |
238 | It is still true that | |
239 | .I learn | |
240 | will not tell the student the right answer. | |
241 | .PP | |
242 | Of course, there are valid objections to the | |
243 | assumptions above. | |
244 | In particular, some students may object to | |
245 | not understanding | |
246 | what they are doing; | |
247 | and the procedure of smashing everything into small pieces may provoke | |
248 | the retort ``you can't cross a ditch in two jumps.'' | |
249 | Since writing CAI scripts is considerably | |
250 | more tedious than ordinary manuals, however, it is safe | |
251 | to assume that there will always be alternatives to the | |
252 | scripts as a way of learning. | |
253 | In fact, for a reference manual of 3 or 4 pages it would | |
254 | not be surprising to have a tutorial manual of 20 pages | |
255 | and a (multi-track) script of 100 pages. Thus the reference manual | |
256 | will exist long before the scripts. |