I remember spin art machines at carnivals and fairs when I was a kid. I loved watching all the patterns and shapes just a drop of paint could make when it moved in a circle.

My son made one with a Tinker Crate project that taught how to build a battery powered circuit that spun a motor. We learned about resistors and their effect on how fast the spin art spun. We first started by adding one resistor in the circuit, and then saw the wheel of the spin art machine spin a little slower. We then added two, and then three resistors to the circuit, and watched as the wheel spun slower and slower. We learned resistors do exactly what their name says. They resist the flow of current. In other words, they slow down the current flowing to the motor, making the wheel spin slower.

While we watched the paint patterns at the slower speeds, it looked a lot like a spider. Then we got the idea to use a spin art machine as rock painting. More specifically to paint a spider on a rock.

If you don’t have a spin art machine, you can just paint your spiders. If you’re outdoors, away from structures or cars, and wearing clothes you don’t mind getting paint on or have an over-sized shirt as a cover-up, try splatter painting!

We found this simple spin art machine. It took a little trial and error, but we were able to find a way to paint the rocks just in time for Halloween!

Once you have made your spiders, try this spider web science experiment testing the tensile strength of various materials.

Materials Needed:

Rocks
Spin paint machine (optional)
Acrylic paint
Paint brushes (if not using a spin art machine)
Googly-eyes and hot glue

If you are using a spin art machine, be sure your work area is outside, far away from structures, cars, or anything you don’t want inadvertently splattered with paint. Just in case!

Step 1: Select 6 to8 the rocks to paint. Wash and towel dry each stone. We used these small white pebbles.

Step 2: Using a hot glue gun, place a small dot of hot glue in the center on one side of a rock. Glue the rock to the center of the spin art machine and let it dry.

Step 3: Draw a circle with the paint provided in the spin art kit, and color it in with the paint.

Step 4: Turn on the spin art machine and watch as the paint slowly moves out away from the center.

Step 5: Turn off the spin art machine, and wait for it to come to a complete stop. Carefully remove the painted rock from the spin art machine. We used a butter knife to slowly peal the rock off. Remember to also take off the dot of hot glue on the spin art machine. Set the rock off to the side to dry. We had a lot of fun painting our rocks! My two oldest sons took turns trying different colors and designs, and this is how all the rocks turned out!

Step 6: Once the rock is completely dry, glue 8 googly eyes to the middle of the spider.

Step 7: Repeat steps 2 through 6 to the remaining rocks.

My kids loved making their spiders, especially trying different colors and designs!

The Physics Lesson

When the paint is spinning, it has the same circular velocity (or speed) as the spin art machine. But when the motor slows down, the paint on the rock continues to move at the same speed. So the paint leaves the rock behind, and keeps moving at the faster speed. When you watch the video, you’ll notice that the paint does not start “dripping” from the paint circle until the spin art machine starts slowing down. At this time, the paint continues to move at the speed the rock had been moving, while the rock slows down. Its the same idea as when you moving in your car, and it suddenly stops. You continue to move forward at the car’s speed before it stopped, but the car immediately stops. If you didn’t have seat belts, then you would continue to move forward, even though the car is not longer moving forward. Good thing we have seat belts!

Related Resources

Use these spiders with the STEM experiment. Become a material science engineer as you test different types of simulated spider webs!

Be a material science engineer with this spider web science experiment – learn about and test for tensile strength and record results on the free lab worksheets.

Make a spider and spider web activity.

Preschool spider activity mats

I hold a master’s degree in child development and early education and am working on a post-baccalaureate in biology. I spent 15 years working for a biotechnology company developing IT systems in DNA testing laboratories across the US. I taught K4 in a private school, homeschooled my children, and have taught on the mission field in southern Asia. For 4 years, I served on our state’s FIRST Lego League tournament Board and served as the Judging Director. I own thehomeschoolscientist and also write a regular science column for Homeschooling Today Magazine. You’ll also find my writings on the CTCMath blog. Through this site, I have authored over 50 math and science resources.