Mix yeast with 1/2 cup warm water in a small bowl, and set aside until yeast begins to foam, for 5 to 10 minutes.
Add remaining water, olive oil and salt, and stir to combine. Using a portable or standing mixer, add flour by cupfuls until a sticky dough comes together. Knead by machine, or put dough on lightly floured work surface and knead by hand for 5 minutes, or until dough is smooth and elastic. Put dough in a bowl, cover with a clean towel and let rise in a warm place for 1 to 11/2 hours, or until doubled.
Punch dough down, and form into equal-sized balls for 2 large or 4 small pizzas. Spray pizza pans or baking sheets with nonstick cooking spray, or rub with olive oil. Let dough rest for 30 minutes, shape into pizza crusts and place in pans or on sheets.