We made dinosaur hats that made everyone roar with delight. These hats are super easy to make. First, I traced a dinosaur on a large piece of construction paper, then I had the children trace that pattern twice and cut out two dinosaurs, then we stapled the two dinosaurs together at the top and plopped the growling guys on each kid's head.
We also learned about teen numbers by using rekenreks to play a game I called "Make My Dino". The first child turned over a "head" and a "tail" card to make a dinosaur (the heads were all ten and the tails were 1-9). Then the second child had to show how many squares were on the dinosaur his/her partner made.
I love using rekenrek's because they are a great way to reinforce the 5 and 10 structure that our number system is built on. They've been an especially great tool in helping my kids with the teen numbers because of how the entire top row moves over whenever a number is in the teens. If you don't have access to a set of rekenreks you can make your own really easily. Here is a set of instructions, all you need is some cardboard, string or pipe cleaners, and beads in two different colors.