The scientists

At the playground.  A sunny day, around 10:30am

Daddy: (pointing to a shadow of a pole) Dominic, Pia, come, look at this. Why is this part of the ground darker than the surrounding?

Pia: It's a shadow. Because the sun doesn't shine there.

Daddy: I'll place this rock just inside the shadow, and we'll come back in a few minutes.  You'll see that the shadow has moved.

After 10 minutes...

Daddy: Come, look at the stone and the shadow

Dominic: Wow, the stone is outside the shadow.  How did that happen?  I think it's because the sun moves.

Pia: (does something with her fingers and then casts its shadow on the ground) Look, a bunny!

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