cooking food requires adding heat energy to the food & adding heat to food usually causes chemical reaction ->  cooking causes a chemical reaction  cooking causes a chemical reaction & baking is a kind of cooking ->  baking causes a chemical reaction  baking causes a chemical reaction & the dough is baked to form the crust of a pizza ->  baking the dough to form the crust causes a chemical reaction  baking the dough to form the crust causes a chemical reaction & chemical reactions cause chemical change -> baking the dough to form the crust causes a chemical change