Draw a big curved line in the sky
Draw a second curved line below it
Keep adding more curved lines under the first one
Make each line a little bigger than the one above it
Use the colors red, orange, yellow, green, blue, indigo, and violet
Color each curved band one at a time
Keep the colors in the same order
Make the rainbow bright and neat
Add clouds at both ends if you want
Draw a sun or raindrops nearby if you like