Start with a pre-made pizza crust (or go here for a delicious homemade version, if you're up for it). Prep your grill for direct high heat and prepare a small bowl of olive oil for brushing on both the grill grates and the pizza crust. Pick your toppings (tomato sauce, mozzarella, herbs, pepperoni, mushrooms, peppers, pineapples, onions...whatever you want!), and at this point, consider letting the kids pick and make their own.
Shape the pizza dough by flattening it with your fingers on a flat, slightly floured surface. Note: do not make a raised rim around the edge of the crust; the different crust thickness will interfere with the grilling process. Place the dough onto a flat cookie sheet that also has a little bit of flour on it so it doesn't stick. The easiest way we've found to get olive oil on the grill grates is to dip a tightly-wrapped paper towel into the olive oil and wipe it onto the grill with tongs.
Once the grill is hot enough (you can hold your hand about an inch over the grill grate for no more than 2 seconds), slide the pizza dough onto the grates and close the lid for 2 minutes. You'll know it's time to flip over the crust when the bottom is slightly brown and the top starts to bubble. Using tongs, pull off the crust onto the cookie sheet, grilled side up. Make sure to reclose the lid to keep the heat inside.
Slide your pizza back onto the grill. If using a gas grill, reduce the heat. If using a charcoal grill, close the cover vents almost all the way. Close the lid and cook for 2-3 minutes. When finished, the bottom should be slightly charred and the cheese on the top bubbling. Slide your now delicious-looking pizza back onto the cookie sheet and prepare for serving.