STEAM: Things that Spin

For the final STEAM activity of the year, I wanted to steer things towards active experimentation instead of just build and play (Transit of Mercury notwithstanding). I did not want to lose the sense of wonder I've been nurturing, however, so quantitative experimentation was discarded for qualitative. Experimenting with something with a surprising property seemed like a good idea as well, so I decided to base an activity on things that spin.

Spinning things, if you've not observed them before, can be very non-intuitive. The simple act of imparting angular momentum gives rise to stability, in most cases, and very unexpected behavior in others. To demonstrate the different behaviors, I assembled a small collection of spinning devices.

They're not toys. They're educational tools.

I started with an Euler's Disk acting as a very large and heavy coin. The "coin" at rest on its edge is inherently unstable and wants to fall over. But when it's spinning, it does not just fall over. The act of spinning the "coin" makes it want to stay upright.

Next, I used the top to reinforce this idea. The top wants to lay on its side when it's at rest. But if it's spinning, it will remain upright.

I then asked if anyone knew how to tell the difference between a raw egg and a hard cooked one (neither shown in the picture), then demonstrated the answer. I also showed that once you've got the raw one going, it doesn't want to stop, even if you halt its rotation momentarily.

I used the plastic egg to demonstrate when you spin an egg-shaped object fast enough it wants to stand on end.

The celt (rattleback) was then pulled out because it is vaguely egg shaped, but it does not act at all like an egg when spun. Especially in the wrong direction.

The dynamic celt was used to explore the action of the celt.

And tippe top was there to keep them guessing.

I then asked the class what they have learned about spinning based on observations of all the items, guiding them to the idea that spinning exerts a force, and the force is proportional to the rate of spin.

To reinforce this idea, I used the gyroscope to demonstrate unusual behavior when things spin really fast. I spun the gyroscope with a Dremel tool (a high speed rotary tool, for those who aren't from countries where the brand name has supplanted the noun) with a felt polishing wheel attached, so I got really good action on it.

After the demonstrations, I told the class I wanted to explore what it is about spinning that creates force. I had the students return to their desks where they found five squares of card stock with a small hole in the middle of each, and a toothpick. "We're going to do some experiments by making a top," I said.

Top, deconstructed.

 The first step was to try spinning the toothpick by itself and observe what happened.

The next step was to add one square about 1/3rd of the way up the toothpick spin that, and observe what happened. I solicited hypotheses from the students as to what they thought would happen when the second square was added.

This process was repeated for all five squares. At the end, I asked the students what they thought was required to generate the stabilizing force in a spinning object.

After that, it was top spinning time. And Euler disk. And plastic egg. Pretty much everything I had brought with me. Fun was had by all, and I got some really good hypotheses from the students about spinning things.

As a total aside, after I had designed this activity, Physics Girl published a video on bizarre spinning toys on YouTube.

STEAM: Spool Racer

How do you top stomp rockets?

The answer is, you don't. Each activity should be judged on its own merits. I figured this out after this STEAM activity.

Searching the Internet for STEAM activity ideas, I came upon HowToons. Of their many projects, I thought the spool racers would be the easiest to do in a classroom, with the least amount of clean up afterwards.

At first I was going to talk about potential and kinetic energy, and maybe touch upon conservation of energy. Then I regained my senses and simplified things down to a single principle. A spool racer is basically an engine. What is an engine? It's something that converts one form of energy into mechanical motion.

I got the class to that point by asking for examples of things with motors or engines in them.

I then told them we were going to build an engine that converts energy stored in a rubber band into mechanical energy, all while winding up my sample spool racer. Then I let the racer go across the table, and the class was hooked.

After that, it was just a matter of building the spool racers, and letting the class play. A lot of spare rubber bands came in handy, too.

Honestly, after the stomp rockets, I thought this activity was going to bomb. Turned out, I was wrong. Feedback from my son was everyone had a great time and liked the spool racers a lot. Having a month between activities probably helped in this respect as well.

STEAM: Stomp Rockets

For my third STEAM activity, I decided to leave the world of mathematics and enter the world of physics. Around the time of this activity, Scott Kelly was returning from his historic (almost a) year in space, so rockets seemed like a good idea.

Scientific American and NASA both have lesson activities around paper rockets with straw launchers. NASA also has an activity with stomp rockets. Stomp rockets seemed like they'd have more impact with the students, but I wasn't sure if we could go outside or not, so I emailed the teacher to ask, and prepared activities around both.

As it turned out, we could go outside, so I decided to do a classroom demonstration with a straw rocket, have the students build stomp rockets (hopefully taking into account the things they learned from my straw rocket demonstration), then go outside and watch them fly.

The activity started with a picture of Astronaut Scott Kelly, describing what he had just done, then asking the students how astronauts get to the International Space Station. With the answer, "rockets", given I announced that we were going to build rockets.

"A rocket is generally a long cylinder to hold all the fuel necessary to get the astronaut into orbit. So what happens if it's just a cylinder?" I asked, producing a pre-made straw rocket with no fins. I launched it across the room and watched it tumble. "Does that seem like a good way to get an astronaut to the International Space Station?" I asked. Everyone agreed that it was not.

"What if we put fins at the top of the rocket?" I produced a pre-made straw rocket with fins at the top of the rocket, launched it across the room, and watched it tumble. "That doesn't seem to help."

"What if we move the fins to the bottom of the rocket?" I again produced a pre-made straw rocket, this time with fins on the bottom and launched it. It flew in a nice, ballistic trajectory. "Does that seem like it could get an astronaut to the space station?" Everyone agreed that it did.

"So let's build some rockets," I said. "Only..." I looked at the straw rocket. "This seems kind of small." I reached into a paper grocery bag I had brought with me and pulled out a stomp rocket. "Why don't we build big rockets then go outside and launch them?" This was met with great enthusiasm.

I demonstrated how to construct a paper stomp rocket, handed out supplies, and let the class build. Once everyone was done (which took longer than I expected), we went outside. I quickly assembled six launchers, showed how they worked, and let the student go. The rest of the time was spent fixing launchers and handing out spare rockets that I had brought with me.

For the launchers, I substituted milk jugs for the two liter bottles that are called for because that was what I had. This turned out to be a bad idea because the jug does not fit well on a 1/2-inch PVC pipe. A two liter bottle seems like it would. The jug connection (I used the cap with a cut out hot glued and duct taped to the pipe) was the weak link in the system, and I was constantly repairing it.

At the end of the activity, I had a number of destroyed milk jugs, no more spare rockets, and a very happy teacher and students.

If you are planning a stomp rocket STEAM activity, bring plenty of spare rockets, and duct tape for repairs.