From MathWeb

A Drill Problem is a math problem that satisfies the following conditions:

1. It isolates a skill. In other words, it addresses a single algorithm or technique.
2. It is repetetive. Given one drill problem, similar drill problems can be made by simple modifications.

When writing a drill problem, one or both of the following guidelines should be followed:

1. Write multiple (5-10) similar drill problems, in order of increasing difficulty.
2. Write a paragraph, describing for a teacher how to create new drill problems.