With my youngest students, we start out standing on dots and hitting balls around the floor. I give them the goal of trying to slap the ball through somebody else's legs. Then we transition into moving around and hitting the ball. Instead of using the word OUT, I say they're TOAST. When they're TOAST, they run over to my mats (which I call the TOASTER), sit down, then stand right back up. I explain that bread goes to the toaster to get better. So if you go to the toaster, come back in even better than when you left. Right away, we have two ways to become TOAST: If the ball hits your legs or if you pick it up. For Kindergarten and First grades, those are the rules. With Second grade, I determine if they can handle adding the other rules and then add them in slowly. Double taps are the hardest to learn so I spend plenty of time introducing the rule and give lots of lee-way with it.