What are some riddles for 11 year olds?

Here are a few riddles suitable for 11-year-olds:

1. What has keys but can't open locks? (A piano)
2. I speak without a mouth and hear without ears. I have no body, but I come alive with the wind. What am I? (An echo)
3. What begins with T, ends with T, and has T in it? (A teapot)

These riddles are fun and encourage critical thinking!