The estimated length of time for the complete lesson is approximately 20 one-hour class periods across content areas. The estimated length of time for each activity within the lesson varies and is listed in parentheses after each Teacher Note. Most activities range from 45 minutes – 1 hour. There are a few activities that range from 15-20 minutes. Times may vary according to your implementation and student discussion time. These estimations include time for students to explore the information in the sidebars.