Amplitude of a Wave

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Students will understand how to measure different wave heights and why this makes a difference.

Big Idea

Students will understand that different waves have different properties.

RAP - Review and Preview

5 minutes

I call students to the gathering area. I remind them that we talked about frequency and amplitude in the first lesson of this unit. I tell them that today we are going to play with amplitude. We are going to explore what the difference in amplitude means for waves.

Independent Investigation

30 minutes

I tell students that they will be working in pairs today. I all students time to choose their partners and then I have them look back to me for instructions. I tell students that each pair will receive a jump rope that I borrow from the PE department.


Students move about the room and practice making waves of different kinds. They can make waves vertically by moving the rope up and down rapidly. They can make waves horizontally on the floor by moving the rope side-to-side on the floor. I ask students to look at the word, amplitude again. I ask them to predict what they think needs to happen to produce waves of higher amplitude. Students record their predictions on their observation sheet. I tell students to make big waves and small waves and observe what happens and what they look like. I have them record their observations on their recording sheet.


I have students watch this YouTube video, that explains how waves move. It helps students to have a frame of reference for the class discussion we have following it.

Guided Investigation

10 minutes

After the video, I ask students to think about the difference in waves as they move away from the initial point. I ask them to think about what is needed to make a particle move through a large distance. Students should answer that it requires more energy. I relate this to amplitude. I tell students that particles have to have more energy to move through a higher amplitude wave. The more the particle moves the more work is being done on the particle. The more work there is, the more energy there is. Thus a wave with high amplitude has more energy than a wave with smaller amplitude.

Wrap Up

5 minutes

I call students back to the gathering area. We talk about the fact that amplitude and energy and work are all related (work is force and distance). I tell them that we will continue to work with waves and energy in other lessons as well.