This simple robot will have your students engineering this adorable rattling robot with its wobbly head!

Materials: electric toothbrush with one AA battery (available for $1 at most dollar stores), pool noodle, plastic knife, washable markers, rubber bands, balloons, permanent marker, googly eyes, paper, duct tape, ruler

Step 1: Install Battery and Test Electric Toothbrush.

Install the battery in the toothbrush and check that it will work when you turn the switch on. Troubleshooting: Double check the battery is in with the negative side down and the positive side up. Make sure the cap is aligned correctly. There are little arrows on the body of the toothbrush and the cap you should line up.

Step 2: Cutting Pool Noodle.

Using a plastic knife, cut off a 7 inch length of pool noodle. If you don’t have a ruler, just measure the pool noddle to be long enough that it can fit the entire toothbrush.

Step 3: Make Wobble Head.

Blow up a balloon. Tie it. Draw a face on it with permanent maker and add the googly eyes.

Step 4: Securing Wobble Head to Electric Toothbrush.

Using half a width of duct tape, secure the balloon nozzle about an inch below the toothbrush cap. Then push the toothbrush all the way into the pool noodle.

Step 5: Secure Markers to Pool Noodle.

Choose at least three markers (in colors of your choice!), and secure them to the pool noodle with a rubber band off the end of the pool noodle with the brush end.

Step 6: It's Alive! Make It Move and Draw.

Uncap the markers and place the rattle writer on a sheet of paper. Turn on the the toothbrush, and watch your Rattle Writer go! Now would be an appropriate time to shout, “It’s alive!” Be sure to give your rattle writer a name. (If you have trouble getting your writer to move, try adjusting the height of the toothbrush or the angles of the markers. Try angling them all slightly.)

Step 7: Engineer It!

Now, think about how you might fiddle with the arrangement of the markers, rubber bands, or toothbrush to create different designs! Use this base model as the foundation to iterate through the engineering design process. What will you change? What impact does it have on the performance of the Wobble Head Rattle Writer?

Challenges

 Can you get the rattle rider to draw a (nearly) straight line?

 How about overlapping circles? Small spirals? Big spirals?

 What other shapes can you get it to draw?

 Can you give your rattle writer arms and legs? Hair?

 Can you make an outfit of clothes for your rattle writer?