I participate in a "mommy n' me" type preschool where I teach two days a week once a month (does that make sense?) This morning I was teaching the kids about water and rainbows and the amazing things that water can do. These are the arts and crafts projects we made to go along with the lesson.
I used six glass bowls and poured 1/2 t. vinegar into each one. Then I added 4-5 drops of food coloring to each one along with 1/2 c. rice and stirred it well. After each bowl was mixed, I separated it into two sets of muffin tins )I didn't want it too deep so that the bottom wouldn't dry/cook. Then I baked the rice at 200 degrees F. for 45 minutes.
I found the basis for the idea HERE but didn't want to have the kids just glue the rice to the paper, so- I pulled out yet another bunch of old baby food jars. We layered the rice in the jars and hot glued the lids shut. The kids spooned the rice in themselves and were so proud! I think they turned out kinda cool!
We also taped the crayons together to create a rainbow that they could easily draw on a large piece of butcher paper and then they glued cotton balls to the base of each side of the rainbow.