Based on the animated story “Mouse in the Treehouse” from the PBS KIDS series MOLLY OF DENALI™, this lesson introduces students to using diagrams. (Move the cursor over the video progress bar to locate “Mouse in the Treehouse” at 01:00.) In the video, Molly and Tooey decide to design and build a treehouse, with Mr. Patak’s help. When their treehouse diagram is unclear, Mr. Patak asks them to include labels—which identify a windmill, elevator, and bunk beds! In the lesson, students examine images related to a current unit of study—images that could be more helpful with the addition of labels. They add labels and leader lines to the images to help readers improve their understanding of the text.