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* *Reflection: Checks for Understanding
Wave Quiz - Section 4: Construct an Explanation on the Doppler Effect

*Doppler Effect Explanation*

*Wave Quiz*

# Wave Quiz

Lesson 11 of 15

## Objective: Students demonstrate their understanding of waves and sound with a summative assessment.

## Big Idea: Waves have properties such as wavelength, frequency and speed and behaviors such as interference and the Doppler effect.

*50 minutes*

A quiz is a good way to assess student understanding of material. It also keeps students accountable for their learning. Today's quiz has content from the last 10 lessons, including wave properties and the wave equation from Wave Hello, wave interference and standing wave from Standing Waves, applications of standing waves from Design Your Own Instrument and the application of the Doppler formula from Doppler Effect Equation. The quiz has has three parts. Part one includes multiple choice with primarily conceptual questions. Part two is made of free response problems, all with a math component. In part three, students have to explain the Doppler Effect and why sonic booms happen when a sound source exceeds the speed of sound.

For today's quiz, students apply CCSS Math Practice 1: Make sense of problems and persevere in solving them,Math Practice 3: Construct viable arguments and Math Practice 4: Model with mathematics. NGSS Science Practice 5: Using mathematics and computational thinking and Science Practice 6: Constructing explanations all in the context of NGSS Performance Standard HS-PS4-1: Use mathematical representations to support a claim regarding relationships among the frequency, wavelength, and speed of waves traveling in various media.

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#### Quiz Procedure

*20 min*

For the first 20 minutes of class, I give students an opportunity to ask any questions that they might have. This time is theirs and they can ask about any of the content covered in the previous lessons. Students ask to review a Doppler effect problem with the Doppler formula. They also ask to do sample problems with the different types of instruments: string, tube open at one end and tube open at both ends.

At the end of Q&A time, students clear their desks. This is a closed note test and students do not have any note sheets. There are only a few equations they need to have memorized for this quiz, so a note sheet is not needed.

My classroom has students seated at tables in groups of four. Because of this, everyone is seated next to someone and across from someone else. So that students do not read the answers off of someone else's quiz, I sometimes create different versions of the quiz or test and alternate them between students. However, for this assessment there is only one version. Students put up manila folder barriers they have at their desks to block their line of site of other students' quizzes.

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For part of the quiz, I give students 11 Wave and Sound Quiz. Multiple choice questions are a good way to determine students' understanding because they are easy to correct and I can ask a lot of questions. This allows me to collect data on specific content areas where there could be persistent student misconceptions or misunderstandings.

The free response problems for the quiz include a few problems that require use of the wave equation, a Doppler effect problem, applications of the wave equation as well as defining parts of a wave. As always, I explicitly write on the quiz that "VFW is required for full credit". VFW stands for

**Variables**: students must list the variables that are given and for which they must sovle.**Formulas**: students must write the formula without the numbers.**Work**: students show their work and mathematical manipulations.

Using VFW has been consistently enforced all year so students are comfortable with this. When we later review the quiz as a class, I model the use of VFW in my Quiz Solutions (the preview only shows the first page, download the document to see the complete solutions).

These problems are representative of the material covered in the previous several lessons and are an important part of any physics student's education.

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It is a mistake to limit assessments to only mathematical applications, as quantitative-style assessments favor a small proportion of students, namely those with strong mathematical and logical abilities. For this part of the quiz, students create an explanation of why the the Doppler Effect occurs on a blank piece of paper. They must lay out their explaination in a logical pattern and include diagrams to support their explanation.

Their explanation must include the following parts.

- The wave equation.
- Wave velocity does NOT change with motion of the observer or wave source.
- Wavelength DOES change with motion of the observer or wave source.

These things, together with a diagram, are the components I am looking for on students' explanation.

Unless a student has an IEP (Individual Education Plan) that requires they get more time, all students get the time allotted to finish the quiz. Most students finish the quiz with a few minutes left in the lesson. They hand in their quizzes to me as they exit the room.

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- LESSON 1: Wave Hello
- LESSON 2: Slinky Rules
- LESSON 3: Standing Waves
- LESSON 4: Standing Waves Demonstrations
- LESSON 5: Resonance
- LESSON 6: Design Your Own Instrument
- LESSON 7: Overtones in Musical Instruments
- LESSON 8: Observations On The Doppler Effect
- LESSON 9: Doppler Effect Equation
- LESSON 10: Wave Quiz Prep
- LESSON 11: Wave Quiz
- LESSON 12: Mixing Colors with Light
- LESSON 13: Electromagnetic Spectrum Mapping
- LESSON 14: What Materials Block Your Phone's Signal?
- LESSON 15: Speed of Light Vs. Speed of Sound