Has anyone tried as an additional technique the "fill-in" method?
This is based on the tried and tested method of teaching called "reverse chaining". To illustrate it, if you are teaching a child to put on a vest, you do not throw it the vest and say put it on. Instead, you put it almost on, and ask the child to do the last bit, and so succeed. You gradually put the vest less and less on, the child always succeeds, and finally can put it on without help. This is called error-less learning and is a tried and tested method, particularly in animal training (almost the only method! ask any psychologist, as I learned it from one).
So we have tried writing out a proof that, say, the limit of the product is the product of the limits, (not possible for a student to do from scratch), then blanking out various bits, which the students have to fill in, using the clues from the other bits not blanked out. This is quite realistic, where a professional writes out a proof and then looks for the mistakes and gaps! The important point is that you are giving students the structure of the proof, so that is also teaching something.
This kind of exercise is also nice and easy to mark!
Finally re failure: the secret of success is the successful management of failure! That can be taught by moving slowly from small failures to extended ones. This is a standard teaching method.
Additional points: My psychologist friend and colleague assured me that the accepted principle is that people (and animals) learn from success. This is also partly a question of communication.
Another way of getting this success is to add so many props to a situation that success is assured, and then gradually to remove the props. There are of course severe problems in doing all this in large classes. This will require lots of ingenuity from all you talented young people! You can find some more discussion of issues in the article discussing the notion of context versus content.
My own bafflement in teenage education was not of course in mathematics, but was in art: I had no idea of the basics of drawing and sketching. What was I supposed to be doing? So I am a believer in the interest and importance of the notion of methodology in whatever one is doing, or trying to do, and here is link to a discussion of the methodology of mathematics.
Dec 10, 2014 I'd make another point, which is one needs observation, which should be compared to a piano tutor listening to the tutees performance. I have tried teaching groups of say 5 or 6, where I would write nothing on the board, but I would ask a student to go to the board, and do one of the set exercises. "I don't know how to do it!" "Well, why not write the question on the board as a start." Then we would proceed, giving hints as to strategy, which observation had just shown was not there, but with the student doing all the writing.
In an analysis course, when we have at one stage to prove $A \subseteq B$, I would ask the class: "What is the first line of the proof?" Then: "What is the last line of the proof?" and after help and a few repetitions they would get the idea. I'm afraid grammar has gone out of the school syllabus, as "old fashioned"!
Seeing maths worked out in real time, with failures, and how a professional deals with failure, is essential for learning, and at the reasearch level. I remember thinking after an all day session with Michael Barratt in 1959: "Well, if Michael Barratt can try one damn fool thing after another, then so can I!", and I have followed this method ever since. (Mind you his tries were not all that "damn fool", but I am sure you get the idea.) The secret of success is the successful management of failure, and this is perhaps best learned from observation of how a professional deals with failure.
One approach for dealing with this problem: make a three-part worksheet. Part one is "stuff using the formulas we just learned today." Part two is "review of old stuff." Part three is "mixed problems."
In essence, when you teach the first concept, the student isn't learning it as an if-then statement: "when you see this, then do this." The student is just learning "do this," because that's the only sort of problem the student sees. So when you introduce the second concept, really the student has twice as many new things to learn - how to solve the second type of problem, and how to distinguish the first type of problem from the second type of problem. Of course there's no getting around this. You have to introduce something first. But that's my theory for why the second thing you introduce makes things slower.
Best Answer
How about this notorious one I remember from high school?
"$f(x)$ is just a fancy name for $y$."