What do Earth Cookies tell us about geology and the past? Objective Students will compare and contrast different types of cookies and igneous rocks and classify them according to their structural make-up and ingredient composition. Background Although the average student is relatively unfamiliar with rocks, especially their composition and formation, most students are very familiar with cookies. In actuality, cookies and rocks have many similarities, especially in the ways that they are formed. For this reason, a careful study of cookies provides a great introduction to rock formation and stru Duration: 90 Minutes.