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ACTIVITY: Surfing the Waves

NGSS Science and Engineering Practices:

NGSS Crosscutting Concepts:

NGSS Disciplinary Core Ideas:

The activity below draws from the content in the page Surfing the Waves.

<p><strong>Fig. 1.</strong> Surfers ride a large wave at Waimea Bay, Hawai‘i.</p>Phenomenon:

When a surfer catches a wave, it pushes them forward.

 

Inquiry:

What are the features of a wave?
Why do waves cause objects to move?

 

Guiding Questions:

  1. What are the features of a wave?
  2. How does knowledge of waves help people use wave energy to move objects, like surfboards?

 

Activity:

Explore waves using a rope and wave tank to describe the wave in terms of its features. Add a 'surfer' to model how the energy stored in waves can cause objects to move. 


Materials:

Part A. Make Rope Waves

  • Tape (about 12 feet)
  • Long rope or extension cord (about 12 feet)

Part B. Make Water Waves

  • A small, floating object

(tinfoil or a bottle cap works well; you can also make your own floating object out shape it to resemble a surfboard or boat)

  • Large clear tray to hold water
  • Straw (preferably metal, glass or silicone to avoid single use plastics)

 

Teacher Recommendations:

  • Rope: longer is better because you can make multiple wavelengths. Due to the friction from the ground, a longer rope will also hold some wave formation when you stop moving it. This allows students to directly see the wave formation, making it easier to label the parts on their worksheet.
  • Ocean basin: using a long, rectangular tray with high sides will provide clear results and prevent water spills. The longer the tray, the more pronounced you'll be able to make the waves (Fig, 2).

<p>Fig. 2. This long, clear container makes for an excellent tank to visualize waves being made.</p><br />
Note: A plastic drawer from a refrigerator, long baking dish, or long window-box planter can work.

Procedure:

Part A. Make rope waves!

  1. ​Practice making a wave that shows the basic features of crest, trough, amplitude, and wavelength. Follow along on your worksheet to answer questions, build, and test your model.
  2. Tape a long straight line on the floor to represent the rope at rest. This tape line should be about the same length as your wave model rope (about 12 feet).
    (Note: You can tape it as a dotted line to conserve tape.)
  3. Line up your rope or extension cord on the taped line and have one person sit at each end.
    (Note: you can also attach one end of the rope to something stable, like a desk, to keep it steady.)
  4. Place a piece of tape around the rope (at about the half-way mark). The tape represents an object (Fig. 3). 

<p>Fig. 3. An example set-up to make waves with an extension cord.</p><br />


  1. Have one person hold their end still, while the other person moves their hand side to side, against the ground, to make waves (Fig. 4).
  2. Practice making waves
    1. Take turns making waves from either side!
    2. Try moving the rope faster. Then, try moving the rope slower. 
    3. Try moving your arm in wider strokes on the ground. Then, try moving the rope in narrower strokes on the ground.
  3. Use your best practice technique to make a wave with your rope. Stop the motion so that the rope stays in its wave shape (Fig. 4).

<p>Fig. 5. If you make waves and then stop your movement, you can see the shape of the wave.</p><br />


  1. Describe the shape of the wave. Write or draw your observations on your worksheet.
  2. Label your wave diagram with the vocabulary below (Fig. 5):
    <p>Fig. 5. Use this template to label amplitude, wavelength, crest, trough, disturbance, direction of energy flow, and motion of an object.</p><br />
Crest the top of the wave
Trough the bottom of the wave
Amplitude The distance from crest of the wave to the still-water level. Some people refer to amplitude as "from crest to rest."
Wavelength the distance from one wave crest to the next.
Where the disturbance occured to make waves (i.e. which side of your rope did you move).
The energy flow from that disturbance.
The motion of an object.

Part B. Make water waves!

  1. Before building your wave tank model to explore ocean waves, think about the last time you were at the beach (or watch waves from an internet beach camera) and answer these questions:
    1. What did the waves look like? Describe.
    2. How big were the waves?
      1. What is the term that scientists use to describe wave height?
    3. Were the waves close together or were they far apart?
      1. What is the term that scientists use to describe the distance between waves?
  2. Now practice making waves in your wave tank! 
  3. Fill your wave tank about halfway with water. Make sure there isn't too much water that will spill over the sides!
  4. Conduct your trials.

Trial #1: Blowing

  1. Using a straw, blow across the water. If you donʻt have a straw, you can use your breath.
  2. Describe what you see.
  3. Play with making different waves by blowing in different directions or with varying strength.

Trial #2: Tilting

  1. Gently lift one side of the bucket up a few inches and lower it back down to the table. 
  2. Desribe what you see.
  3. Did your wave have a large or small amplitude compared to trial #1?
  4. Did your wave have a long or short wavelength compared to trial #1?
  5. Play around with making different waves and see if you can create repeating patterns in the wave energy.
    (Hint: lift the bucket a little higher, or lift it twice in a row. Be careful not to spill water out of the bucket!)

Trial #3: Add an object

  1. Add your floating object on one side of the bucket.
  2. Make waves by blowing as you did in trial #1. Be sure not to blow directly on the object, but instead keep it directed at the water!
  3. What happened to your object? How did it move?
  4. Make waves by tilting, as you did in trial #2.
  5. What happened to your object? How did it move?
  6. See if you can get your object to move to the other side of the container.

 

  1. Can you see the similarities in the waves you made with the rope with the waves in your wave tank?

Activity Questions:

  1. Describe the general motion of the waves you created.
  2. How did the waves change in amplitude and wavelength when you:
    1. Blew harder?
    2. Tilted the bucket higher?
  3. What would be different if you had a longer tank? 
  4. How were your waves similar to ocean waves breaking on the shore? How were they different?
  5. What happened to the floating object when you made waves?
  6. Did your object catch and move forward on every wave you made? If not, in what directions did the object move on the waves it did not ride?
  7. How is the motion of your floating object similar and different from a surfer waiting to catch a wave in real life?

Table of Contents:

Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.