Let's play at guessing riddles!

Every year I give my students a handout with five or six riddles. In groups of four they have to guess the riddles in 15 minutes. They can use a dictionary, too. They say it is very entertaining!

What has roots as nobody sees,
Is taller than trees,
Up, up it goes,
And yet never grows?

#Answer: mountain

Thirty white horses on a red hill,
First they champ,
Then they stamp,
Then they stand still.

#Answer: teeth
You feel it, but never see it and never will.

#Answer: heart

You must keep it after giving it.

#Answer: your word

As light as a feather, but you can't hold it for ten minutes.

#Answer: your breath


Has a mouth but does not speak, has a bed but never sleeps.

#Answer: river