This Problem Set is a part of the Lesson 23, Unit 7, Grade 8. Using square roots, students determine the position of the bottom of a ladder as its top slides down a wall at a constant rate. The purpose of this optional extension lesson is to incorporate the knowledge obtained throughout the year into a modeling problem about the motion at the bottom of a ladder as it slides down a wall. Many questions are included to guide students' thinking, but it is recommended that the teacher lead students through the discussion but allow them time to make sense of the problem and persevere in solving it throughout key points within the discussion.