### Summary

Students will use springs to investigate the quantitative characteristics of waves. Then, they will use their data to derive the formula connecting frequency, wavelength, and velocity. Later, students will connect those math ideas to an example from nature. This lesson is Part 2 of "Beyond the Slinky®," a three-part lesson series on waves and their properties.

### Essential Question(s)

How do you measure a wave?

### Snapshot

**Engage**

Students listen to a spectrum of tones and speculate why the tones sound different.

**Explore**

Using a long, skinny spring, a Slinky® toy, and a rope, students create different properties of waves and make drawings in their notebooks.

**Explain**

As a class, students discuss the characteristics of waves using the proper terminology.

**Extend**

Students calculate the characteristics of waves using math problems in a real-world survival scenario.

**Evaluate**

Students revisit the spectrum of tones from the beginning of the lesson and add academic language to their written explanations of why the tones sound different.

### Materials

Lesson Slides (attached)

Why Do the Tones Sound Different? handout (attached; one per student)

Wave Activities handout (attached; one per student)

Outsmart the Bat handout (attached; one per student)

Bat Cards (attached; one card per student)

Long, skinny springs (one per group)

Slinky® toys (one per group)

Meter sticks (two per group)

Stopwatches or timers (one per group)

### Engage

Introduce the lesson using the attached **Lesson Slides**. Display **slide 3** to share the essential question and go to **slide 4** to review the lesson objectives with students.

Go to **slide 5** and pass out the attached **Why Do the Tones Sound Different?** handout. Inform students they will listen to audio and then use the Bell Ringer portion of the handout to answer the question.

Invite students to stand up, and let them know they should sit down when they start hearing a high-pitched noise. Then, play the video “How Old Is Your Hearing?” starting at the 1-minute mark. Even after everyone sits down, let the video play until 1:31 so that students can hear the full range of sound.

Give students a few minutes to write their responses to the question "Why do the tones sound different?" in the Bell Ringer box. When time is up, ask students to hold on to their handouts for use later in the lesson.

### Explore

Organize students into groups of three or four. Pass out the following materials to each group:

Long, skinny spring (often referred to as a snaky or helical spring)

Slinky® toy

Two meter sticks

Stopwatch/timer

Go to **slide 6**. Pass out the attached **Wave Activities** handout either to each student or to each group, depending on how you want students to collect data.

Have students explore only the concepts of amplitude, frequency, and wavelength in these activities—the next portion of the lesson is when they will learn the academic terminology to discuss these concepts further.

Have students follow the directions on the handout to complete the activities. Provide additional guidance as needed.

### Explain

After students have completed the Explore activity, bring the whole class back together. Inform students they will use academic language to describe what happened with their springs.

Display **slide 7** to show students what happened when they moved their springs up and down—use the diagram to explain how this movement created a transverse wave. Next, go to **slide 8** and give students time to draw a picture of the wave on the slide.

Go to **slide 9** to introduce the academic language used to describe and study waves. Give students time to label their drawings correctly and add definitions of the terms on the slide.

Then, go to **slide 10** and ask students to answer the following questions based on their findings from the Explore activity:

What is the relationship between wavelength and frequency—is it proportional or inversely proportional?

What is the relationship between frequency and velocity—is it proportional or inversely proportional?

Based on this information, can you write a formula connecting wavelength, frequency, and velocity?

The first two questions should lead students to derive the formula that connects wavelength, frequency, and velocity. Though it may be tempting to “help” students by giving them the formula, ask for student volunteers to share their ideas instead and make refinements to reach the answer through student input.

### Extend

Display **slide 11** to introduce a problem that students need to solve using their knowledge of waves. Play the “Moth jamming bat” video.

Pass out the attached **Outsmart the Bat** handout to each student. Once students have read through it, inform them you are the “bat” who will “fly around” and give each student a frequency. With the **Bat Cards** in hand, move around the room and give one card to each student.

Go to **slide 12**. On the handout, have students attempt to figure out the life-saving wavelength they need to produce to throw off the bat and avoid being eaten.

Once students have arrived at their answers, have them work in groups and try to replicate the wavelength with their springs.

After a few minutes, ask students if they struggled to replicate the wavelength. (The answer should be yes.) This is your chance to guide them through the scaling process. After they scale, have them try to replicate the wavelength again.

### Evaluate

Display **slide 13** and have students get out their handouts from the beginning of the lesson. Have students first look over their Bell Ringer answers, then ask students to respond to the following prompt in the Exit Ticket box:

*Based on what you’ve learned, describe the relationship between wavelength, frequency, and velocity and explain how that relationship reveals why the tones sound different. *

When students have finished writing their answers, you may collect their handouts to assess what they have learned.

### Resources

Barracuda1983. (2006, June 3). Pipistrellus pipistrellus in flight [Image]. Wikimedia Commons. https://commons.wikimedia.org/wiki/File:Pipistrellus_flight2.jpg

Corcoran, A. (2013, September 23). Moth jamming bat - National Geographic untamed Americas [Video]. YouTube. https://www.youtube.com/watch?v=GZxK_0OSoFk

Joe N Tell. (2019, February 4). How Old is Your Hearing? - Interactive Test for Your Ears [Video]. YouTube. https://www.youtube.com/watch?v=iN3PBpInNJM

K20 Center. (n.d.). Bell ringers and exit tickets. Strategies. https://learn.k20center.ou.edu/strategy/d9908066f654727934df7bf4f505d6f2