My students made shadow sticks to investigate how a shadow changes throughout the day.  They know that it appears the sun is moving across the sky.  They did not know that the sun doesn't move.  (Now they do!) They created a shadow stick to see how a shadow changes size throughout the day based on the position of the sun in the sky.  Morning, longer shadow.  Noon, shorter shadow.  Afternoon, longer shadow.  All of this was fun for them and a good idea, but with every good idea comes challenges.  For the next 2 days, it was cloudy.  We could not see our shadow until after we took our unit assessment.  They were able to take their shadow stick home to investigate over Fall Break.