In this lesson students practice using what they know about vertical, complementary, and supplementary angles to calculate the sizes of various angles. The teacher concludes by presenting the formula for finding the sum of the interior angles of any polygon.

• Part 1: Presenting and Checking Warm-Up Problems [Begin: 00:01]
• Part 2: Checking Homework [Begin: 05:13]
• Part 3: Assigning Seatwork [Begin: 14:59]
• Part 4: Providing Extra Help on Challenging Problems [Begin: 26:19]
• Part 5: Checking More Homework and Introducing a New Formula [Begin: 32:40]
• Part 6: Previewing the Upcoming Schedule [Begin: 41:08]
• Lesson Table: The lesson table contains a detailed summary of the lesson's mathematical content.