Wagon Jr. learned really quickly! I put the tissue up to his nose and instructed him "go like this" and blew air out of my nose. He did it with his mouth first, and I said "no, close your mouth and go like this" and did it again, and he did it! He did it again once more before bedtime and got a ton of snot out. Just in time too, he's having his first runny nose of the season.