Willie Wombat's Walk

Willie Wombat is in early elementary school and isn't invited to a birthday party. He feels left out and like he is the only one not invited. Then he discovers, one by one, he is not the only one. All of those, who were not invited, all felt alienated and like they were the only ones not invited. So Willie discovers, quite by accident, that a strategy to deal with not being invited, is to find and make more new friends, one at a time.