There are plenty of things you can do, but
PLEASE DO NOT DO THE FOLLOWING:
Leave the room.
Once you arrive, stay until the last kid from your hour leaves.
Bring your own food in the room.
That's just bad manners to eat in front of other people, even if they are little kids.
Use your phone.
You are an important part of the team. Texting does not help the kids or other volunteers in your room, so don't do it.
Check kids out.
Only adult volunteers in the room should do this.
Roughhouse with kids.
Swinging kids by their arms, legs, ears or any other appendages, or tickling. (Yeah really. No tickling.)
Be alone with a kid.
That's not safe for you or the child. You should always be in the room with at least one other volunteer. Do not take a kid alone to the bathroom, resource room or anywhere else.