The Secret Life of Prime Numbers
It’s not magic. By color-coding different
combinations of factors, students can learn to use this system to “guess”
unknown, randomly selected integers and composites.
This is available to members of NCTM. If you are interested in a NCTM membership, join now. You may also purchase this article now for online access.
Putting a twist on a popular mathematical tool, this collection
of activities shows how putting a number 1 in the bottom-left cell and a 100 in
the top-right cell can better support student reasoning.