Tim: Hi, Joe. What are you doing?
Joe: I'm drawing. Look! This is me. And that's my shadow.
Tim: Wow! Your shadow is long.
Joe: Yes. It is evening in the picture. The sun is going down. My shadow is long and thin.
Tim: When is the shadow short?
Joe: At noon, the shadow is short. Because the sun is above our heads.
Tim: Wow. How interesting (有趣的)!
Joe: Yes. You can go to the playground and have a look at your shadow now.
Tim: Good idea. Look, my shadow is long too.
Joe: Yes. Because it's morning.
