I laid the number cards out face up and called out the numbers for the students to smash (hit with their hand.) Since there were two sets, each child could find a number pumpkin to smash. We took turns calling out numbers and smashing pumpkins- giggling and laughing all the while.
Then, I called out the numbers for the students to collect in their hands starting with 11 asking, "What number comes next?" When they got to 20 we mixed up the pumpkin cards and I asked them put them in number order.
I had one child close their eyes and I removed a pumpkin card from their number line. "What's missing?" After they got the hang of this, I let them partner up with each other and play together. They were begging to play this game again the next day! I say, "Smash on, smart pumpkins!"