I posted a while ago on using a CD and a flashlight to make a rainbow for Kalina. Here's a cool youtube video on how to measure the spacing of CD grooves using the same principle ( Read more... )

Kalina wanted a rainbow. She reads care bears books, and they're forever jumping around on rainbows. So she wanted Daddy to make her a rainbow. My first thought was to spray mist from the garden hose and make one that way. But the sky was overcast, and I didn't think we'd have enough direct sunlight ( Read more... )