Building on the work of the previous lesson, in this lesson students practice determining when an equation is an identity.

The Warm-up is meant to help students make sense of the following activity (MP1), where they investigate an identity that can generate Pythagorean Triples. In the last activity, students prove identities involving rational equations as they learn about Egyptian fractions and consider different ways to rewrite a fraction as the sum of unit fractions.

This lesson includes an optional activity to use if students need additional practice proving algebraically that an equation is an identity.