You can make a blue shadow.
Think about it...
Think about it some more...
I'm serious. I saw it with my own two eyes!
Experiment with opaque and translucent objects outside.
Balloons - different colors
Saran Wrap of various colors/shapes
Bottles of water - various sizes, shapes, and colors of water.
Shadows are caused by objects blocking light. However, if the object is transparent (see-through) or translucent (kind of see-through), some light is passed. We're so used to seeing shadows cast by us that we sometimes forget that shadows aren't necessarily black or just of human form. We were walking home from a dinner this weekend where J was given a blue balloon. It was so neat to see blue with our own family of shadows!
Try to make different shaped shadows or depict a story in shadows. Then trace it with some sidewalk chalk or take a picture.