#MathArtChallenge Day 64: Anamorphic Raintangle (from woollythoughts.com)

The challenge: Create a rainbow and get it reflected in a curved surface to reveal a rectangle. All credit here to Woolly Thoughts! (They have wonderful things for you to play with there.)

Materials needed: I crocheted mine, which was a fun puzzle to get an even rainbow. They have knitting instructions on their website, but you could just as easily draw this with markers. I used tinfoil as my reflective surface wrapped around a nail polish remover bottle. I bet you all get more creative than myself. Math conceptsyou could explore with this challenge: circles, geometry, perspective, proportions/ratios

Depending on how you use this activity, you may engage with different mathematical standards. I’ve listed possible connected math content above. Here are a few suggestions for how you might integrate the 8 mathematical practices. Feel free to add your own suggestions in the comments!

3.) Construct viable arguments and critique the reasoning of others. Create an argument that if the rainbow is uniform and the reflector is uniformly curved, there will always be some angle that results in a straight reflection.

6.) Attend to precision. How much precision is needed here? Is it possible that a poorly made rainbow would still make a straight rectangle if just shown at the right angle?