When I get my 2 year old involved, I start by pouring the half-cup of sauce on each flat bread, and I've her a large spoon to spread it around. I help her spread it to the edges.
Next, I have her spread the shredded cheese on top - however much people want (her daddy likes a lot of cheese, I like some under the veggies and some over top.) The cheese should come just shy of the edge, otherwise it burns when you bake it.
I give her the veggies and meats in bowls and let her "decorate" the pizzas according to how each family member likes it. Her daddy likes sliced meatballs, I like lots of veggies. You can add anything at all - anchovies, pineapple and ham, shredded chicken and broccoli.
Put the pizzas on a cookie sheet or pizza stone in a very hot oven - mine goes up to 550 degrees. Bake for 10-12 minutes, or until the cheese is melted but not browning. Remove from the oven and allow to cool for 5 minutes.