- The Well-Chosen Rectangle, a grid-paper approach to fraction arithmetic, presented in text, graphics, and video. It is an extremely accessible big idea with many uses, a complement to any other techniques.
- More on this, in a blog post.
- Companion applets: Fraction Rectangles.
Slices: Worksheets to make connections between fractions, angles, time, money, percents, and decimals — using the "pie slices" representation, including an applet to make your own graphics. Particularly helpful to illustrate questions like "what is `2/5` of 60 minutes?"
The Egyptian Fractions Challenge — a great example of a rich, high-ceiling, non-random practice and problem reversal. Appropriate for students who have mastered the basics of fraction arithmetic.