Rube Goldberg, YouTube, and the Archimedes Screw: Hidden Drivers of Pedagogic Transactions

In Edith Ackerman’s paper “Hidden Drivers of Pedagogic Transactions: Teachers as Clinicians and Designers,” she shows that as teachers take on the role of clinicians (facilitating communication around a problem) and designers (imagining and creating a safe learning environment for exploration and negotiation of old and new thoughts), a pedagogic transaction takes place between the teacher and the learner, in which both parties are shaped by and shape a problematic situation.

I would like to share a learning experience that took place between me and a small group of my 5th and 6th grade students, which can serve as another example that shows what Ackerman stated, “that learning occurs because participants are jointly engaged in exploring, expressing and negotiating ideas [on a topic that matters], because they create and use external forms as a means to mediate ideas and experience, and because they come at it from different angles.”

It started with a small group of students (5th and 6th graders) who I was coaching to prepare for the county Rube Goldberg competition. The team of 8 students had broken up into smaller teams of two to build separate components of their Rube contraption, which had a Route 66 theme. The story that their machine was to follow centered around an imaginary family going on a road trip along Route 66, from Chicago to San Bernardino. Their project had already included various setups of inclined planes with cars traveling “cross country.” However, I knew, as well as the students, that their project needed a “wow” factor, something to be engineered so creatively that viewers of their project would be highly impressed. We decided to look at the idea of simple machines from a different perspective, and where else do eleven- and twelve year-olds look for new ideas and inspiration other than YouTube?

Off to YouTube the children went, watching Rube Goldberg videos, looking for something different. At first the children were growing in excitement by seeing other ideas, but as I probed them to think deeper about what they were seeing (e.g., “Is that really a new idea?”,  “Is that a unique use of a simple machine?”), they realized they continued to see a lot of the same, old thing. Inclined planes with objects rolling down, pulleys being activated and releasing an item to the next location, wheels and axles rolling along. I went home that night and decided to do some of my own YouTube research. I came across a video in which cans rolled upward along an inclined plane. Now, this was something quite different- it almost looked like magic. The next day, I showed them the video in slow motion, and we watched the cans rolling upward multiple times, analyzing the movement, attempting to figure out how it worked. The students came to the conclusion that some sort of magnet must be involved. Nevertheless, their challenge was set before them. They needed to include SOME way for SOMEthing to roll UPWARD.

Back to YouTube they went. They wanted to find more examples. Now at this point, of the 8 team members, 3 were assigned the task to figure out how to make something roll upward, so only 3 students YouTubed their way through their challenge. After about 20 minutes on YouTube, they came across an example of a cardboard Rube Goldberg project in which a small marble was deposited at the bottom of an Archimedes screw and traveled upward along the screw to be deposited at the top of the machine, where it would then continue to travel downward along the typical Rube inclined plane setup. This was what the students wanted to accomplish.

So, they got to work. Student #1, who I will call Monica, was the small team’s artist. She began sketching the contraption they wanted to build. Student #2, who I will call Moses, continued to analyze the video to try to figure out how the Archimedes screw worked. Student #3 ended up leaving the group to help other teams and never returned.

As a side note, I’d like to mention that none of the students ever read the description of the video, in which the word “Archimedes screw” was used. They went along for weeks not knowing that what they were attempting to build was called an Archimedes screw. It was really fun to have them later read about Archimedes and learn the history behind the design they were to build.

Back to the story. After Monica and Moses were done sketching and analyzing, they searched the room for materials. They came to me with a clear plastic pipe that we had lying around the lab- I believe it is the type of plastic pipe that is used for encasing electric cords to keep them in place. It was just one of many random items I had purchased at Home Depot the month before that I figured may be used for something or another over the course of building the Rube Goldberg machine. They wanted to use the plastic pipe as the center of their screw.

Next, they needed to add the rounded inclined planes, the screw, around the plastic pipe. They thought of cutting cardboard out into strips like in the YouTube video and came to me for advice. I probed them with a simple question, “Why struggle with scissors and thick cardboard such as this when we have thin sheets of cardboard that can easily be cut with our laser cutter?” Their eyes widened and they set to work. They retrieved our digital caliper to start measuring the diameter of the plastic pipe. Then, they measured the diameter of the ball they wanted to use (a small 3D printed ball I had lying around the lab, similar in size to a ping pong ball). Then, they logged into CorelDraw (a graphic design software) and with a little reminder from me on how to set their lines to RGB red and Hairline, they sketched a circle to match the diameter of the pipe, and then another circle to match the diameter of the pipe + the diameter of the ball. They included one straight line to connect the two circles, which had the same centerpoint, and they sent it to the printer. It was done in 15 seconds. They tested it out, and sure enough, it fit perfect and snugly around the plastic pipe. They went back to CorelDraw to duplicate their drawing multiple times, enough to fit the sheets of cardboard we had, and printed multiple sheets of these circles.

Laser Cut cardboard spirals to create a screw around a plastic pipe

I’m going to fast forward a bit here. Basically, they were able to create a “screw” with their plastic pipe and many, many laser cut cardboard “donuts.” Their next hurdle was to make this pipe rotate. Luckily, we had a few windshield wiper motors in our lab leftover from last year’s animatronics projects. I suggested to them that if they could find a way to mount their screw to the motor, the motor would rotate the screw for them. The problem was that their pipe was hollow- it had no bottom or top that could be attached to the motor. Coach Emerson to the rescue. “If you could find a way to solve your last problem by designing something to be lasercut, don’t you think you can find a way to solve this problem by designing a part we could print?”

Now, for this task, Monica and Moses needed a lot more of my help. With the last task, they were able to find the tools they needed mostly on their own and were able to design what they wanted in CorelDraw because they were both very familiar with the program, from previous classes they had with me in which I taught them CorelDraw. For this new problem, they would need to use SolidWorks (an advanced CAD software, used primarily in the manufacturing industry), and neither Monica nor Moses had used SolidWorks in over a year. So, we sat down together, each at our own computer with our notebook, the caliper, and the plastic pipe. We discussed together, with a lot of my probing (“What is it that you need to design?”, “How should it look?”, “What features does it need?” “Is this what you expected it to be?”) and came up with a sketch of what we wanted. We took measurements of both the inner and outer diameter of the pipe and came up with a cup-like design, basically an extruded cylinder base with a hole in the middle to screw to the motor, and two more raised, hollowed cylinders to encase the sides of the pipe. The pipe would sit inside this cup-like design and be screwed to the motor.

These are initial sketches and calculations before designing in SolidWorks.

This is Monica’s close up sketch of the part to attach the screw to the motor.

This is the 3D printed part that was attached to the windshield wiper motor.

For the next step, they needed to learn how the motor actually worked. Monica and Moses did not participate in the animatronics project from the previous year, so they sought out another student whom I will call Bianca, who was known to be the electronics expert of the team. She had worked on a number of the motors during the animatronics project the year before and easily taught Monica how to set up the wires so the motor would run. They tested it out and it worked! The motor successfully turned the screw, however, they immediately noticed a new problem. Because their screw was so tall, it swayed outward and did not stay directly upright while being moved by the motor. So, they decided to use two wooden dowels spaced purposefully at the exact distance from each other to hold the ball from falling off the edge of the screw. This idea they got from the YouTube video. This would keep it in place on one side, but did not stop the screw from swaying outward. So, with the help of my colleague Richard, who probed them to think about securing the screw from the top, just like they had on the bottom, they duplicated the part they had already printed to mount the screw from the bottom, added a top to the part that could spin inside a small hole, similar to how a gear spins in place, and it was now secure! They tested everything out, and it finally worked. They completed their challenge to have an object move upward, creating that unique almost “magical” effect that we knew their project needed.

In the end, they took their project to competition and placed second place against other teams of mostly 7th and 8th graders. We were all very proud of their accomplishments, but what I know to be the most powerful aspects of this project are all of the “transactions” of learning that took place between these students and myself. We designed solutions to problem after problem, using and manipulating technology and tools at our fingertips, and I was able to design, immediately and authentically, challenges that stretched my students’ minds and allowed them to mediate and share new ideas with each other.

3D Printed Pipe Holder Drawing

3D Printed SolidWorks Dowel Holder Drawing