My class has been really into Shadow Play for the past two weeks - it's part of a parent gift that we'll unveil very soon (so stay tuned!) We have a dark spot under the reading loft that is just right for exploring shadows.
I put out this tray filled with flashlights, chalk, scissors, tape, and black paper. There are also several books for the library that show how to make animals using hand shadows.
Here, the kids are working on tracing their own shadows (or silhouettes, as we now call them).
The invitation to explore shadows has inspired mini-shadow puppet shows, great conversations, and cooperative learning. Once you start looking for shadows, you find them everywhere!