1. Warm Up Question: Brian shows two tuning forks of different lengths on the projector. He asks students to provide descriptions, explanations, and drawings showing the differences in sounds that would be heard when these two tuning forks are ringing. Brian puts a few samples of student work under the document camera to share their responses. This provides one last opportunity for students to refine their thinking before starting their individual assessments.
2. Individual Evidence-Based Scientific Explanations: Students work on a writing assignment where they explain how two listeners (one in the front row and one in the back row) at a rock concert would hear sounds from different instruments. Brian builds off of students’ previous group assignment and asks slightly different questions on the individual assignment: Explaining Sound at a Concert.

Discussion Questions:1) How does Brian use this lesson to help students wrestle with unobservable ideas that the students had not necessarily considered to date? 2) What other phenomena might students be able to explain now? 3) How does the scaffolding on this individual assignment compare with the scaffolding provided on the previous small group assignment? Why did Brian make these assignments slightly different? 3) Create an explanation rubric and evaluat  students’ evidence-based explanations of sound heard at a concert, detailing partial as well as complete understandings