real science for today's homeschooler

Earthquake Waves

Earthquake Waves

The general properties of waves can be investigated through an activity on earthquakes. First, have your child research the three different types of earthquake waves. Encourage them to find the following information about each wave:

1. name of the wave

2. how quickly it travels compared to the other two

3. what part of the Earth does it travel through

4. type of wave, based on motion (compression wave, transverse wave, etc.)

5. does it cause damage to buildings

Help your child organize the information they find into a chart or data table. This can be done on the computer or by hand. Or, make a poster and add pictures and drawings. Use the chart to compare and contrast the three types of earthquake waves.

Next, have your child build a structure that will withstand the different types of earthquake waves. (Encourage them to look at the type of motion caused by each wave.) Use any type of materials such as building blocks, boxes, DVD cases, etc. In order to test their construction, have them build it on a surface that will be easy to move, such as a small table, board, etc.

Test the structure(s) by recreating the various motions of the different earthquake waves:

P waves – move the surface back and forth in a horizontal motion

S waves – move the surface up and down

L waves – move the surface in all different directions, including circular motion

Older children may then want to research how scientists are designing earthquake resistant buildings.

Share this on...Email this to someoneTweet about this on TwitterShare on Facebook

Slinky Waves

Slinky Waves

Have an old slinky collecting dust in the kids’ toy box? Pull it out and teach a quick lesson on the two types of waves.

1. Loosely stretch the slinky across the floor or long table with you holding one end and your child holding the other.

2. Create a transverse wave by shaking one end of the slinky horizontally across the floor or table. Continue shaking back and forth to set up a series of transverse waves that will move from one side of the slinky to the other.

3. Have your child identify the crests and the troughs of the waves.

crest and trough

4. Also explain that in a transverse wave the energy moves perpendicular (at right angles) to the motion of the medium. They can see the medium (the slinky) move side to side while they feel the energy being transferred from your hand to theirs. Help them to see that the motion of slinky and energy are in different directions.

5. To make a longitudinal or compression wave, make a quick shoving motion with the slinky toward the person at the other end. You should be able to see a compression travel along the slinky between your hand and the person on the other end. Continue making compression waves in the slinky for your child to observe.

6. Have your child identify the compression and the rarefaction (see below).

compression and rarefaction

7. Explain that in a longitudinal or compression wave the energy moves in the same direction as the motion of the medium. In this case, they should see that both the slinky and the energy from your push are both traveling in a straight line between your hand and theirs.

If you are trying this with small children it may be difficult for them to identify the motion of the medium vs the energy. At lower grade levels, just focus on the fact that there are two different kinds of waves and how they look different. If your child is ready for new terms, help them identify the parts of one or both types of waves.

Finally, for all children, extend the lesson to brainstorm where they have observed (or how they can make) transverse and longitudinal waves in different types of media (water, rope, air, etc.)

Share this on...Email this to someoneTweet about this on TwitterShare on Facebook

Make Waves in the Tub

Make Waves in the Tub

Light waves . . . sound waves . . . it’s all pretty hard for a younger elementary student to understand. They can see light and hear sound, but the wave part just isn’t something they can perceive with their senses. A good way to begin to introduce the topic of waves is with water waves. A wave that is visible and moves slowly enough for them to observe the actual wave itself.

Use bath time as a way to introduce the topic of waves to your younger child. Here are some basic wave properties that can be observed in the tub:

1. Have your child make a series of waves in the water and observe. The highest point in a wave is called the crest. The lowest point is the trough. As you make waves toward your child, have him/her point out or try to catch a crest and a trough.

2. The distance between the crest of one wave and the crest of the next wave is the wavelength. Have your child experiment to find a way to make waves with a long wavelength and then with a short wavelength. Talk about what determines the size of the wavelength. (How fast the child moves determines the wavelength. All waves are caused by vibrations. The speed of the vibration determines the wavelength.)

3. The distance between the height of the crest and the midpoint of the wave (the water level if there were no wave) is the amplitude. Have your child experiment to find a way to change the amplitude of the waves. Talk about what determines the size of the amplitude. (Amplitude is actually determined by the amount of energy in the wave. The more energy your child puts into making a wave, the larger its amplitude will be.)

Through this bath time activity, your younger child will learn the basic parts of a wave and two fundamental wave properties. And, they will be a little cleaner, too! 🙂

Share this on...Email this to someoneTweet about this on TwitterShare on Facebook