The estimated length of time for the complete lesson is about 12 days. The estimated length of time for each activity within the lesson varies and is listed in parentheses after each Teacher Note. Activities range from 20 minutes – 2 hours, but times may vary according to your implementation and student discussion time. Depending on your schedule, some activities may be completed over two class periods or portions may be completed at home. These estimations include time for students to explore the information in the sidebars.