Growing Rainbow Experiment This experiment gives plenty of observation time as kiddos watch 2 sides of a rainbow grow together and make one big rainbow! Find more about this experiment here! Material ready! Kiddos will love working with the markers! Draw a rainbow on each side of the towel! Don't leave too much space between the 2 rainbows or they may not 'grow together' well. Fold the coffee filter. Put each side in a cup with a bit of water. Then it's observation time! This would also be a great time to read the paired book....The Color Monster! This is a great book to help kiddos relate to emotions. Wow! Look at the rainbows growing together! Want to pair this experiment with a book? Try The Color Monster! Grab the book on Amazon! (affiliate link) Here's the recording sheet we used! Click the pic to download a copy!