Ken's interval

re: study time and retention intervals

I would think it is even more efficient to systematically fade both the amount of problem and the interval between problem sets for each new problem type.

For example after a new problem type is learned via massed practice, subsequent practice sets might go something like this:

day 2: problems 10
day 3: problems 10
day 4: problems 8
day 5: problems 8
day 6: problems 6
day 7: problems 6
day 9: problems 6
day 11: problems 6
day 13: problems 6
day 16: problems 5
day 20: problems 5
day 25: problems 5
day 30: problems 5
day 40: problems 4
day 50: problems 4
day 60: problems 4
day 80: problems 3
day 100: problems 3

That's how the the spiral should work. As the student better learns the material, it gets refreshed at increasingly larger before the knowledge has a chance to fade from memory.

This is how Engelmann does it in all the DI programs. The only exception is when a subskill gets subsumed into a more complicated skill (once it has been mastered), then only the more complicated skill gets the distributed practice.

Saxon is interesting in this respect, because Saxon books give you practically no massed practice at all once you move to algebra. Prior to that kids to "Fast Facts" sheets every day.

In the high school books students do, at most, 4 or perhaps 5 problems in the new skill or concept covered in the lesson. Usually you do only 2.

I assume he does this because by the time you get to algebra you're constantly doing problems built out of well-learned embedded skills, but I don't know.


overlearning overrated?
how long does learning last?
shuffling math problems is good
Saxon rules
Ken's interval
same time, next year
remembering foreign language vocabulary