Sound Review

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Students will be able to solve and explain problems involving concepts of sound waves.

Big Idea

Students turn into teachers today when they demonstrate their knowledge about sound waves.


As our unit on sound comes to an end, this lesson is meant to provide students a comprehensive review before they take the unit exam. The class starts with students solving a ranking task and a discussion of the solution. Then, students use their computational thinking skills (SP 4-6) to collaboratively solve and share problems involving the speed of sound, interference, and the Doppler Effect (HS-PS4-1). After students are finished working through their problems and sharing the solutions, the class ends and students should be well prepared for their unit test on sound. 

Introduction with a Standing Waves Ranking Task

10 minutes

Because this lesson is a cumulative review before tomorrow's test, today's introduction provides students a chance to self-assess their comfort level with sound. When students walk into the room the standing waves ranking task is already projected onto the screen at the front of the room and there is a copy of the handout for each student. I choose this particular ranking task because it is a question related to the wave speed of standing waves on a string.

Once the students are settled, I read the instructions from the top of the activity (see the strategy demonstrated here). My reading of the instructions is to ensure students understand that class has started. I emphasize to students that they should work individually and take about five minutes to rank the waves, explain their reasoning, and then assess their level of confidence. During these five minutes of work time, I walk around the room and informally assess how students are doing with simple glances at their work. My changes in location help students stay quiet and focused.  

When the five minutes are over, I reveal the answers to the students by writing the solution: B, F, D, A=C, E onto the front screen. I then ask if anyone knows and is confident in their solution. Since my students are fabulous, inevitably there is at least one who did and is willing to admit it. It's that student that I then ask to explain his reasoning. If the explanation is complete and clear, I commend the student! In the event the explanation needs to be expanded, I contribute any missing information so the whole class has a complete understanding of the material. Regardless, I end the introductory activity by reminding students that conceptual questions like these are an important component for success on the unit and AP Physics 1 tests.

Students Collaboratively Solve Sound Problems

15 minutes

Today's class uses collaborative problem solving as a way for students to review forces. Students are each given a different problem from a review problem set. These problems are taken from our textbook and are problems that I feel are most representative of the test questions. Students stay at their lab tables for this activity so we don't lose time while they get into groups and I give each group one of the problems with its final answer. The problem that each group receives is random: I literally walk down the center aisle and give the group whichever problem is on the top stack of my pile because all of the students should be able to answer any of these questions.

I include the answer with each problem (not the solution, but simply the numerical answer with units). The purpose in doing this is that I want students to worry less about getting the correct answer and more about their ability to prove and justify that answer. The AP Physics 1 exam places great emphasis on justifying answers, so I want students to have an opportunity to orally practice the justification process.

My expectation is that students take about fifteen minutes and actively work together to write down the solution on the paper I pass out to them. Without giving students too many details, I tell them to be prepared to not only show their solutions, but to also be able to explain their solutions. Also, I encourage students to use pen as they work. Using pen keeps them from erasing, so even if they make a mistake or change their thinking I can see evidence of their entire thought and solution process.

As students are working at their lab tables, I walk around and ensure that everyone is engaged in the discussion and thinking critically about their problem. I give students hints as I observe, but my feeling is that by this point in the sound unit, students can independently work through these problems. If a group happens to finish early, they can either help a group seated near them or have time to individually review and prepare for the unit exam.

Students Share Sound Solutions

25 minutes

After the collaborative work time is over, I ask students to present their solutions to the rest of the class. Each group comes forward, puts their problem with the solution under the document camera, and explains their solution to the rest of the class. The goal of this activity is to show students the variety of problems that are on the unit exam.  

Because my students are sometimes shy, I ask if any groups volunteer to go first. There is always at least one group that wants to get the presentation out of the way, so I choose them and applaud them for being so willing. This first group of students walk to the front of the room and place the problem with solution under the document camera. One person from the group must read the problem aloud so the entire class becomes familiar with that problem, as they have not seen it before. A second student should explain any diagrams that were drawn and the list of given information. Finally, a third student from the group verbalizes the solution that has been written on the paper.

Once the solution is appropriately provided, I ask the class if they have any questions for the group. If someone from the class does need to ask a clarifying question, or if I need to ask a clarifying question throughout the solution sharing, I expect that any presenting group members who haven't participated yet answer these questions.

Once that first group is finished, I let them pick which group shares next. This chosen group comes forward with their problem and solution, shares, and appropriately answers questions as the last group. The process repeats itself until all problems are shared. Class ends after the last group shares and students have all of their questions answered. If students took good notes throughout this review, they now have a great study resource of new questions with solutions.