Here's what you'll need...
Paper plate
Scissors
Cotton balls
Glue
Here's how you make it...
1. Prepare you paper plate by cutting it in half and then cutting out a small semi-circle from the bottom to make a rainbow shape.
2. Now it's time to paint on your rainbow. You can put any colors you'd like on your rainbow, in any order. However, if you want to be precise with your colors you can layer them as follows: Red, orange, yellow, green, blue and purple.
3. Once your paint is dry you can glue on your cotton ball clouds to each end of your rainbow.
Most paper plates have a glossy finish on the "eating" side of the plate, the back does not. The paint takes better on the non-glossy side of the plate, so keep this in mind when doing your craft, and have to kids paint their rainbow on the back of the plate.