21 questions to ask your kids. Oh, I can't WAIT to hear the answers to these. Write them down and give as a gift. Can work for fathers or grandparents too. Can even ask the same questions a few years down the road and see how the answers change.
Marble Races with a cheap pool noodle (occupies the kids for hours.) Did this, but instead of cutting the pool noodle, the marble is small enough to fit inside the full noodle to roll down. Then can use the noodle for other things too!