Dissolve yeast with 1/2 teaspoon sugar in warm water; let stand 5 minutes or until "proofed". When puffy, add 2 tablespoons olive oil to the mixture. In the bowl of a food processor combine 3 and 1/2 cups of the flour with 1 teaspoon salt. When well combined, add the yeast water and process until a dough forms. If dough is too dry, add a tablespoon of water to the dough and process until a tacky ball forms. If dough is too wet, add more flour a tablespoonful at a time, or until dough is tacky. Turn dough out onto a board and knead for a minute. Turn dough into a lightly oiled bowl, cover with plastic wrap and let double in volume, about 45 minutes. Punch dough and pizza is ready to be formed and baked.
Preheat oven to 500 degrees. Divide dough into 2 halves. On lightly floured surface roll each half into a 12inch circle, as best you can. Transfer each to a large baking sheet and pinch up a 1/2 inch rim around the outside edges of each pizza.
For kids: Sprinkle 1/2 of grated cheese on bottom, and top with some spaghetti sauce, then dot remaining cheese on top.
For adults: Sprinkle bottom of dough with half of cheese, then scatter zucchini, shrimp and sun-dried tomatoes and top with remaining cheese. Bake on middle racks for 10 to 15 minutes, until pizzas are golden (switch baking sheets between shelves half way through baking time so they cook evenly).