Answer:
Halo of water, tongue of wood. Skin of stone, long I've stood. My fingers short reach to the sky. Inside my heart men live and die.
Upon me you can tread, though softly under cover. And I will take you places, that you have yet to discover. I'm high, and I'm low, though flat in the middle. And though a joy to the children, adults think of me little.
What stays on the ground but never gets dirty?
You can hold it without using your hands or arms. What is it?
What gets closer when you blink?
Written on with words of white, Has the color of the night, Is the teacher's best delight, And a student's daily fright