This problem might be found in any

This problem might be found in any standard textbook. It clearly involves important mathematics, but in its present form, criteria 2, 3, 4, and 5 are not as clearly included. By making a quite modest revision, we can open up the problem and by doing so raise the cognitive demand (criterion 2) and also satisfy criteria 3 and 4: Revised problem: What is the sum of the measures of ÐA, ÐE, and ÐC? In addition, we might ask students to find the sum of the three angles in different ways and make generalization of the problem by asking: What is the sum of the three angle measures if point E is at different locations (as shown in the figures below)?