In the curriculum for David and Goliath, the kids can make a towel slingshot.

Now, the curriculum tells you to have each kid hold one end of the towel and a third pull back the socks and let go.
This is one way to do it. And, it works.

However, we were playing with it the other day and discovered another way to sling the socks. And, the leader can do it by himself and have the kids chase the socks. Wouldn’t that be fun!