For my daughter's Girl Scout Silver Award project, she constructed a jumbo (8' x 8') outdoor checker board for a local summer arts camp.
I LOVE this! It's a Buddy Bench. Children can go sit on it if they are feeling lonely or have nothing to do at recess. Other children that see someone sitting there are supposed to invite anyone sitting there to play. And lonely children that find each other there can invite each other to play! What a great idea!
Girl Scout Silver Award Project Ideas | eHow
Sound marble run
Childhood 101 | Games for kids: Tic tac toe - make your own easy sew felt version. Great for travel.