The Rainbow Fish is a story about a fish that is too proud of his beautiful, shiny scales to play with other fish. A blue fish comes along and asks for one of his scales, and the rainbow fish gets angry and says no. He starts to wonder why others are treating him so rudely, and eventually he comes to a perfect solution by sharing his scales.
This is a great story to do in first or second grade; you can do an activity for labeling the parts of a fish, and coloring the scales. You can also do this in kindergarten and discuss why it is important to share.