Dear Karl + others:
I agree and disagree. I don't know who observed that after about
7 minutes of lecture the attention span of students is over and I dont
know how they observed this. But, even if this may be true, I do not
advocate class periods of 7 minutes (the total information communicated
would be zero). But this will also apply to similar activities: if we
go to see a theater play, or a concert or a sport event - which are
longer than 7 minutes. So, what is the conclusion???
I think it is essential that the teacher should CONSTANTLY pull
the attention of students. This can be done during a lecture by
changes in the tone of voice or in the body-motion (like an actor on
stage). Also changing the focus of attention, for example: "Now let us
see how we can apply this theory to a very easy example - what would
you say is an easy example to check the theory?". Grammatically,
the question form makes students feel more involved:"How do you feel
in a car making a violent turn? Like if somebody is pulling you to
the side! Isn't it true?". The strongest change is of course the change
of type of activity, for example after explaining, let then work on
a related problem.
I also taught those dreadful evening classes, once a week, from
7 to 9:30 p.m. Since I was convinced, from the beginning, that constant
lecturing = sleeping from 7:30 to 9:30, I organized my classes more
or less as follows.
1) 10 minutes reviewing what we did last class. 2) 30 minutes
lecturing on something new. 3) 10 minutes questions from students.
4) 30 minutes students working on some related problems. 5) 15 minutes
coffee or sodas brake. 6) 15 minutes going over the problems they
just did before the brake, discussing them in detail. 7) 20 minutes
lecturing on a new subject. By that time it usually was 9:30, since
the timing never worked out as expected. Also: not all classes were
similar in timing, and you adapt to the subject. But I think you
got my message about how to fill the time trying not to loose
the students.
Regards Emilio