We made rabbits out of little r. Using watered down glue, we brushed the pink r with glue and shook rice on top.
Rainbow R: I never took a picture of the final result, but basically you glue strips of color onto the R and then turn the R over and cut it out. We then glued that R onto cardstock.
Rainbow bottles: my colors completely disappeared but I used oil, water, and alcohol and colored them. the kids shook them and then watched them separate.
We also did Rhythm Sticks to music and Ribbon Dancing in the hallway. For snack: a Rainbow made out of fruit!