Introduction: Sound Waves on a Speaker: Goo Dance Party!

About: Science, Technology, Engineering, Art, and Math (or STEAM) programs at Boston Children’s Museum foster children’s curiosity, creativity, and learning as they try things out and explore the world around them.

At Boston Children's Museum, this activity inspires and delights visitors of all ages. Exploring how sound waves affect oobleck is a great way to encourage critical early science skills, while also getting pretty silly. There are many variations on this activity and we hope that you will share your results with us!

Overview: Investigate sound waves by hearing, seeing, and feeling! Listen to the music, feel the vibrations, and watch your oobleck dance around.

Skills focus:

- Observing

- Predicting

- Using senses

Recommended Ages: 4+

Step 1: Materials

For Oobleck:

- Corn starch

- Water

- Mixing bowl

- Spoon

Other Materials:

- Subwoofer speaker (here’s the one we used)

- Mini digital amplifier (here’s the one we used). This should come with a power cord.

- Stereo to RCA audio cable (here’s the one we used)

- At least 1-2 feet of speaker cable

- Tablet, smartphone, or computer

- Plastic wrap

- Rubber band

- Wire strippers

Step 2: Setting Up the Speaker

Using the wire cutters, cut about 12 inches of speaker wire. Strip the plastic coating off of both ends of your piece of wire. When stripped, the ends should look like Image 1. You can split the two sides apart as well.

Next, take out your speaker. You may have noticed that one side of the wire is marked by a black line. This wire will go in the black fastener on the speaker; the other will go in the red fastener (see Image 2).

Step 3: Setting Up the Amplifier

The amplifier (amp) should come with a power cord. Plug this into the appropriate place on the ‘control panel’ area of the amp. Do not plug it into a power source yet.The other end of this cord will eventually plug into the headphone jack of our tablet.

Next, we plug the aux cord into the amp. Our aux cord and amp are color-coded; red plugs into the red input and white plugs into the white input (see Images 1-3). The other end of this cord will eventually into the headphone jack of our tablet. Yay color-coding!

Step 4: Connecting the Amp to the Speaker

Again, there is some color-coding involved here. The speaker wire with the black stripe goes into the black (-) speaker clip. The wire without a stripe goes into the red speaker clip (+).

Step 5: Protect the Speaker!

Cut a piece of plastic wrap and fasten it over the speaker with a rubber band. Don't fasten it too tightly, the plastic wrap should have some give to it.

Step 6: Make Oobleck

Mix 1/2 cup of cornstarch with 1/4 cup of water. Stir until most of the clumps are dissolved. Now you have Oobleck! This substance is a non-Newtonian Fluid (watch this great video to learn more!), which means that it is a fluid with a viscocity and flow that makes it seem to exist in multiple states of matter. In this case, the Oobleck behaves as both solid and liquid.

Step 7: Add the Oobleck to the Speaker

Scoop about 2-4 tablespoons of Oobleck onto the plastic-wrapped speaker.

Step 8: Turn the Bass Up!

Plug the power cable into an outlet and plug your music playing device into the aux cord. Cue up a sub-woofer-heavy soundtrack. We recommend searching "sub-woofer test" on YouTube and experimenting with the top results (here is one of our favorites). Check the amp to make sure that the bass is turned all the way up.

Hit play and watch your Oobleck dance! Can you feel the sound waves? Can you see them? What will happen if you pause the music? What will happen if you play a different song? What will happen if you turn the bass down? This is a great activity to encourage children to make predictions!

Step 9: Next Steps

For younger children:

- Encourage toddlers to play with and explore the Oobleck. Messy sensory activities are great for young learners!

- To demonstrate sound waves in action, we played a metal singing bowl for toddlers. They loved feeling the vibrations on the sides of the bowl. You could create a similar effect with a cymbal.

- Younger children had a great time watching the Oobleck dance on the speaker. Have them control the pause/play button to experiment with cause and effect.

For school-aged children:

- Add things to the Oobleck! We tried adding drops of food coloring, beads, and googly eyes.

- Will this experiment work with other substances? We tried water, sand, and beads in the place of Oobleck.

With this activity, the sky is the limit. What else can you experiment with? Comment below to share your ideas!