home *** CD-ROM | disk | FTP | other *** search
- .NH
- Educational Assumptions and Design.
- .PP
- First, the way to teach people how to do something
- is to have them do it. Scripts should
- not contain long pieces of explanation; they should
- instead frequently ask the student to do some task.
- So teaching is always by example: the typical
- script fragment shows a small example of some
- technique and then asks the
- user to either repeat that example or
- produce a variation on it.
- All are intended to be easy enough that most students will get most questions
- right, reinforcing the desired behavior.
- .PP
- Most lessons fall into one of three types.
- The simplest presents a lesson and asks for a yes or no
- answer to a question.
- The student is given a chance to experiment before replying.
- The script checks for the correct reply.
- Problems of this form are sparingly used.
- .PP
- The second type asks for a word or number as an answer.
- For example a lesson on files might say
- .IP
- .I
- How many files are there in the current directory?
- Type ``answer N'', where N is the number of files.
- .R
- .LP
- The student is expected to respond (perhaps after experimenting) with
- .LP
- .I
- answer 17
- .R
- .LP
- or whatever.
- Surprisingly often, however, the idea of a substitutable argument
- (i.e., replacing
- .I
- N
- .R
- by
- 17)
- is difficult for non-programmer students,
- so the first few such lessons need real care.
- .PP
- The third type of lesson is open-ended \(em
- a task is set for the student,
- appropriate parts of the input or output are monitored,
- and the student types
- .ul
- ready
- when the task is done.
- Figure 1 shows a sample dialog that illustrates the last of these, using two
- lessons about the
- .I cat
- (concatenate, i.e., print) command taken
- from early in the script that teaches
- file handling.
- Most
- .I learn
- lessons are of this form.
- .KF
- .TS
- box, center;
- c.
- T{
- Figure 1: Sample dialog from basic files script
- .sp
- (Student responses
- in italics; `$' is the prompt)
- .nf
- .sp
- A file can be printed on your terminal
- by using the "cat" command. Just say
- "cat file" where "file" is the file name.
- For example, there is a file named
- "food" in this directory. List it
- by saying "cat food"; then type "ready".
- $ \fIcat food\fR
- this is the file
- named food.
- $ \fIready\fR
-
- Good. Lesson 3.3a (1)
-
- Of course, you can print any file with "cat".
- In particular, it is common to first use
- "ls" to find the name of a file and then "cat"
- to print it. Note the difference between
- "ls", which tells you the name of the file,
- and "cat", which tells you the contents.
- One file in the current directory is named for
- a President. Print the file, then type "ready".
- $ \fIcat President\fR
- cat: can't open President
- $ \fIready\fR
-
- Sorry, that's not right. Do you want to try again? \fIyes\fR
- Try the problem again.
- $ \fIls\fR
- \&.ocopy
- X1
- roosevelt
- $ \fIcat roosevelt\fR
- this file is named roosevelt
- and contains three lines of
- text.
- $ \fIready\fR
-
- Good. Lesson 3.3b (0)
-
- The "cat" command can also print several files
- at once. In fact, it is named "cat" as an abbreviation
- for "concatenate"....
- .fi
- T}
- .TE
- .sp
- .KE
- .PP
- After each correct response the computer congratulates
- the student and indicates the lesson number that
- has just been completed, permitting the student
- to restart the script after that lesson.
- If the answer is wrong, the student
- is offered a chance to repeat the lesson.
- The ``speed'' rating of the student (explained in
- section 5) is given after the lesson number when the lesson is completed successfully; it is
- printed only for the aid of script authors checking
- out possible errors in the lessons.
- .br
- .PP
- It is assumed that there is no foolproof way
- to determine if the student truly ``understands''
- what he or she is doing;
- accordingly,
- the current
- .I
- learn
- .R
- scripts
- only measure performance, not comprehension.
- If the student can perform a given task, that is deemed to be ``learning.''
- .[
- skinner teaching 1961
- .]
- .PP
- The main point of using the computer is that what the student
- does is checked for correctness immediately.
- Unlike many CAI scripts, however, these scripts provide
- few facilities for dealing with wrong answers.
- In practice, if most of the answers are not right the script is
- a failure; the universal solution to student error is to provide
- a new, easier script.
- Anticipating possible wrong answers is an endless job, and it is really
- easier as well as better to provide a simpler script.
- .PP
- Along with this goes the assumption that
- anything can be taught to anybody if it can
- be broken into sufficiently small pieces. Anything
- not absorbed in a single chunk is just subdivided.
- .PP
- To avoid boring the faster students,
- however,
- an effort is made in the files and editor scripts to provide
- three tracks of different difficulty.
- The fastest sequence of lessons
- is aimed at roughly the bulk and speed of a typical tutorial
- manual and should be adequate for review and for
- well-prepared students.
- The next track is intended for most users and is roughly
- twice as long. Typically, for example, the fast track
- might present an idea and ask for a variation on the
- example shown; the normal track will first
- ask the student to repeat the example that was shown
- before attempting a variation.
- The third and slowest track, which is often
- three or four times the length of the fast track,
- is intended to be adequate for anyone.
- (The lessons of Figure 1 are from the third track.)
- The multiple tracks also mean that a student repeating a course is unlikely
- to hit the same series of lessons; this makes it profitable for a shaky
- user to back up and try again, and many students have done so.
- .PP
- The tracks are not completely distinct, however.
- Depending on the number of correct answers the student has given for the
- last few lessons, the program may switch tracks.
- The driver is actually capable of following
- an arbitrary directed graph of lesson sequences, as discussed in section 5.
- Some more structured arrangement, however, is used in all current scripts
- to aid the script writer in organizing the material into lessons.
- It is sufficiently difficult
- to write lessons
- that the three-track theory
- is not followed very closely
- except in
- the files and editor scripts.
- Accordingly,
- in some cases, the fast track is produced merely by skipping
- lessons from the slower track.
- In others, there is essentially only one track.
- .PP
- The main reason for using the
- .I
- learn
- .R
- program rather than
- simply writing the same material as a workbook
- is not the selection of tracks, but
- actual hands-on experience.
- Learning by doing
- is much more effective
- than pencil and paper exercises.
- .PP
- .I Learn
- also provides a mechanical check on performance.
- The first version in fact would not let
- the student proceed unless it
- received correct answers to the questions
- it set and it would not tell a student the right answer.
- This somewhat Draconian approach has been moderated
- in version 2.
- Lessons are sometimes badly worded or even just plain wrong;
- in such cases,
- the student has no recourse.
- But if a student is simply unable to complete one lesson,
- that should not prevent access to the rest.
- Accordingly, the current version of
- .I learn
- allows the student to skip
- a lesson that he cannot pass;
- a ``no'' answer to the ``Do you want to try again?''
- question in Figure 1 will pass to the next lesson.
- It is still true that
- .I learn
- will not tell the student the right answer.
- .PP
- Of course, there are valid objections to the
- assumptions above.
- In particular, some students may object to
- not understanding
- what they are doing;
- and the procedure of smashing everything into small pieces may provoke
- the retort ``you can't cross a ditch in two jumps.''
- Since writing CAI scripts is considerably
- more tedious than ordinary manuals, however, it is safe
- to assume that there will always be alternatives to the
- scripts as a way of learning.
- In fact, for a reference manual of 3 or 4 pages it would
- not be surprising to have a tutorial manual of 20 pages
- and a (multi-track) script of 100 pages. Thus the reference manual
- will exist long before the scripts.
-