What are the properties of waves?

Target: 4th Grade

Learning Goals for Students:

  • Students will be able to describe wave properties
  • Students will be able to compare wave properties
  • Students will model wave motion and analyze the affect different materials have on wave properties

NGSS

4-PS4-1 Develop a model of waves to describe patterns in terms of amplitude and wavelength and that waves can cause objects to move.

Cross Cutting:

Pattern

Engage

Allow students 2-3 minutes to pair share what they know about waves. Provide question prompts on the board. Spend about 5 minutes asking several pairs of students to share an answer with the class.

  1. How many types of waves can you name?

Answers: The most common answers may be water waves, light waves, and sound waves.

  1. What do all waves have in common?

Answers: The most common answers may be wavelength, crests and troughs, patterns, and vibrations.

  1. What would a wave on a spring look like? Sketch it.

Answer: Most students may sketch a transverse wave. The transverse wave and longitudinal wave are shown on the springs below. If students only sketch the transverse wave, you may want to show them the longitudinal wave.

Explore

  • Have metal springs, plastic springs, and ropes on a table.
  • Organize students into teams
  • Allow time for students to make waves on the springs and/or ropes
  • Guide students to make observations and describe the waves they produced – you may want to ask questions like:
  1. What did you do to create the wave?

Possible Answers

  • Shook the spring/rope
  • Moved the spring/rope up and down (or side to side)

Students used vibrations to create the waves

  1. What did the wave look like?

Possible Answers

  • It looked like a wave on the ocean
  • It had crests and troughs
  • It looked like a snake

Most students may create a transverse wave, either in the air or on the floor. Ocean waves look like transverse waves.

A transverse wave on the floor may look like a snake.

  1. How would you describe one cycle of the wave?

Possible Answers

  • It had bumps
  • It wiggled
  • It had crests and troughs

One cycle is a wavelength and it means both parts of the wave, the crest and trough, or the up vibration and the down vibration, have been seen.

Explain

Utilize power point, textbook readings, or other material for students to define the properties of waves. After students have been presented with the material, have students write the definitions for each wave property (wavelength, period, frequency, wave speed, amplitude), and develop a model (a sketch) of a wave.

"Waves and Their Properties" power point

Discipline Specific Review Content for Teacher:

Wave Properties

Waves are a disturbance, a vibration that moves through a medium and produces a visible pattern. The wave pattern has properties that can be measured. The medium is the material through which the wave travels. Wavelength is the length of one cycle, crest to crest for a transverse wave and compression to compression for a longitudinal wave. Period is the time it takes for two successive crests or two successive compressions to pass you. Frequency is the number of wave cycles passing you every second, it is the number of crests or compressions you observe in one second. Wave speed is the wavelength divided by the time it takes for that wavelength to pass you; this will determine how fast the wave is moving. Amplitude is the amount of vibration, how high the crest is or how condensed the compression is; amplitude is the energy of the wave.

Standing Waves

When two or more waves are traveling in the same area and material, the wave amplitudes will add together. Waves adding together may have an increase in amplitude if the crests or compressions occur at the same place. Waves may also subtract from each other. Waves may have a decrease in amplitude if the crest of one wave occurs at the same place as a trough from another wave, or if the compression of one wave occurs at the same place as the rarefaction of another wave. Standing waves are alternating additions and subtractions of amplitude as a wave and its reflection are combined. When the waves add, there is maximum vibration, and when the waves subtract there is no vibration.

Water Waves

Water waves look like transverse waves. Although the water molecules move in circles, rather than up and down or side to side, the wave properties can be measured in the same way as we measure transverse (up and down) wave properties.

Elaborate

Activity 1: “Waves on a Slinky & Waves on a Jump rope”

The instructor may want to download an app to his or her phone to measure decibels prior to this activity.

This activity will take students 60-90 minutes to complete.

Activity 2: “Ripples in the Water"

This activity will take 20-30 minutes to complete.

Evaluate

Homework: Ask students to choose 3 items at home, such as a shirt or water, which could be used to create waves. Ask them to create a wave on each item, if possible, and to analyze and compare these waves.

Questions for students to answer:

1)What were your items?

2)Were you able to create waves on each of them?

3)On which item were you able to create the most wavelengths?

4)On which item were you able to produce the highest amplitude wave?

5)Based on your observations, which of the 3 items would be able to make jingle bells ring the loudest?

Ciardi, Teresa College of the Canyons K6 Science Institute1