What can you do when you board as a kid?

Answer 1

If you are "board" as a kid, there isn't much at all you can do. A "board" is a stiff plank of wood. A child who is a stiff plank of wood isn't able to do much at all.

I suspect you meant bored though. Then it is a different matter.

Boredom is a choice; you choose to do nothing. It takes very little really to occuply a mind. You could read. Take a walk. Lay on your front lawn and look through the grass. Watch an anthill. Maybe you could play a game or be with friends, and keep them from choosing to be bored as well.