Sally's shadow is sharp, and the lamp post shadow is fuzzy. Why?
If the sun were smaller, or much farther away, shadows would be sharp.
But the sun is not a dot in the sky -- it looks like a disk (Don't Look At the Sun!). So its rays are not all travelling exactly the same direction. This gives a fuzziness to the shadows, as shown below:
You can also see from this drawing that the width of the fuzzy zone gets wider as you move farther from the object making the shadow. Now look at Sally's picture again:
