Note: This lesson is part of this unit’s Anchor Layer. It builds off of the first four lessons in this unit. If you have the Anchor Layer turned on, we recommend teaching the first four lessons of this unit in order. The performance task can be completed at any time after the fourth lesson.

The anchor phenomenon for this unit is a water-filled cave that contains footprints, fossils, and ancient fire pits. How can these things be found deep underwater?

During the introduction, students generate observations and questions about the phenomenon and create an initial conceptual model to explain how and why they think this is happening.

Students will gather clues during and after each lesson in this unit to help them improve their explanations. It is important to encourage students to recognize that even if they don't know the perfect answer yet, they are going to learn a lot throughout the unit and will have an opportunity to change or add to their first explanation.