Backyard Brains is live from inside the classroom of Colegio Alberto Blest Gana in Santiago to present you 5 group projects we did with our students and the methodology we used to choose the projects. This high school has been like a second lab for Backyard Brains, where, hand in hand with the students, we test much of our equipment, beta test our hardware prototypes, and invent new classroom exercises. This year was the first year where we had students do independent group projects, with a class size of about 15 students, ranging from 7th grade to high school seniors.
It can be a challenge to involve students in independent projects when it is their first time, so it is important to let the students conceive their own project ideas from the beginning. The ideas need to come from inspiration, not mandated from above. That’s why, to help out in the creative process, we devised an interview that would work like a conversation, where the student can start to imagine what they would like to build, or what problem they would like to solve. You can use this pdf as a guide
To guide some shy students that weren’t sure what they wanted to build, we suggested projects that the students could modify so that they could begin to feel that the idea we gave them is also their own. We then place the people that had similar ideas and interests into the same group. As a suggestion, if you are working with students with very different ages, it is important to mix it up a little in this area: always have a mix of older students with younger students.
The interview resulted in 5 projects:
The Electrocardiogram of the Clam.
The project was chosen by students that had an interest in animal physiological systems, and we suggested studying clam electrophysiology. Most of the students didn’t know before this experiment that a clam has a heart, because when you open it, the clam’s organs just look like a blob. It isn’t easy to notice distinct anatomical parts that look so different from the organs of vertebrates. After finding the heart, a challenge for students (and even for us teachers), we needed to make sure the heart was still moving and contracting. Unlike a vertebrate heart, the beat is not like a regular clock, it can stop a long time and then restart again.
When we saw a heart beat, we placed one red signal electrode in the atrium and the other in the ventricle. The third electrode (ground-black) was placed farther away the clam. These three electrodes were connected to the Backyard Brains Heart and Brain SpikerBox to make the recordings.
And glory of glories, we had success!
However, we don’t know if what we recorded is in fact an artifact arising from relative movement of the recording electrodes, giving rise to a baseline shift that mimics in some ways the P and QRS features of a typical ECG. Our next step is to manually deform the heart to see if similar features arise. If not, then perhaps we observed a real biologically-generated clam electrocardiogram. You can download our recording here.
In this project, we used the electricity generated by voluntary muscle contraction to take over the keyboard of a computer.
The appeal of this project is that muscle interfaces work like a charm, a microcontroller is easy to program, and it’s all very low cost. To accomplish this, we decided to control a very easy and accessible video game with the electrical impulses of the muscles, using our Muscle SpikerShield combined with the Arduino Leonardo. The advantage of an Arduino Leonardo is a computer can recognize the Leonardo as a keyboard input. The video game we chose was Google Chrome’s offline dinosaur video game: you can play it fine with only one key on the keyboard (the space bar makes the dinosaur jump…though pressing the down arrow key also makes the dinosaur duck). It’s fun, and you don’t need internet or any specialized gamer hardware to run it. You can download the code here.
The idea of this project was to build a labyrinth to learn about cockroach behavior and food preferences. Could they learn the route to reach a preferred food source faster over time, say, a banana slice instead of a potato slice?
Unfortunately, this project was done in the open air during winter, with a temperature of 40-50 degrees Fahrenheit, a temperature at which cockroaches are not that hungry and not highly active, so using food as an incentive didn’t work. Also, another problem was that the cockroaches were able to climb the walls of the labyrinth. Nevertheless, the students got over these obstacles and had success with one experiment: they placed a lid on half of the labyrinth to make that section dark, and left the other half uncovered, so light could get in. They released the cockroaches, and after one minute, all of the three cockroaches were in the dark side, just like Anakin Skywalker. A small sample size, but convincing evidence of what was suspected all along: cockroaches prefer dark spaces.
The Polygraph Lie Detector.
This project was from a group of students interested in the physiology of lying. At Backyard Brains we love to extract and read physiological signals, and as the traditional polygraph measures skin conductance, respiration, blood pressure, and heart rate, building a DIY polygraph is right in our wheelhouse. To keep it simple in the beginning, we decided to focus on skin conductance alone, something we have been asked to study before many times.
When someone lies, there is the hypothesis that the persons subtly increases sweating. Since sweat is salty water, and salty water is much more conductive than dry skin, we should be able to measure a decrease in skin resistance across the palms when a person is lying.
The first experiment we did was very simple. We checked the skin resistance using a multimeter and patch electrodes across our inner palms before and after running on the treadmill The results were the following:
Before running 5 kilometers
After running 5 kilometers (24 minutes)
The results are crystal clear, a body covered in sweat is much less resistant to electrical current than dry skin.
The next step was to find a way to graph skin resistance in real time, and test it using lies instead of jogging. The students made a simple circuit in Arduino where the grey cables go from 5 V input to analog 0 in arduino, buuuutttt, the cable is cut and the person must grab each end of the cut cable with each hand. They then used the sample code “graph” which graphs the voltage value of the analog input, which, of course, will change depending on the resistance of the skin across the student’s hands.
When we tested using lies, there was no significant change in the value of the skin resistance, as the effect is simply too subtle, if it even exists at all, to measure using our equipment. Although the final test wasn’t successful, at least we tore down the myth that galvanic skin response can detect lies by itself. That’s why complete polygraph machines also measures respiration, blood pressure and heart rate, and the combination of all these elements supposedly makes the polygraph a more reliable tool for detecting lies. If we continue this project in the future, we will look into integrating these other physiological signals in addition to skin conductance.
Muscle Electrophysiology in soccer.
This group of students was interested in how electromyography changes when making different strength kicks in soccer: kicks made for small distances, like close passes, and kicks made for big distances, like aiming for the goal or to a player that’s far away. To do this, we placed two signal electrodes in the abductor muscle of the quadriceps, and the ground on the knee. We then placed masking tape in the floor, marking the distance in meters, and the subject kicked the soccer ball to a friend waiting at the various meter marks.
The different distances we used were 5 meters (16.4 feet), 3 meters (32.8 feet), 15 meters (49.2 feet), 20 meters (65.5 feet), 25 meters (82 feet), 30 meters (98.5 feet), and 35 meters (114.8 feet). Below is a sample of the data they recollected:
As you can see quite nicely, the amplitude of the EMG of the quadriceps increases as the soccer ball kicks become more forceful. This was our hypothesis, that as you recruit more and more muscle fibers during a movement, the EMG signal amplitude will increase due to the higher number of action potentials generated and the superposition that results.
This experiment on the physiology of sports was very fun for the students. We also tried baseball pitches, but the rapid “snap-back” movement of the arm would always cause the cables attached to the triceps to come flying off. With basketball, we did not notice a dramatic difference between two point and three point shots. So, as the students were happy to report, for now, soccer is the best for studying the physiology of sports using our equipment! We will keep trying with baseball for all the Detroit Tigers fans out there.
These final projects were worked on once a week, for 1.5 hours, for 2.5 months, and on October 30th, the students presented their results to the community to much success. The sports physiology and the clam EKG experiment will be the first to be transformed into formal Backyard Brains experiments on our webpage, so stay tuned! If you are interested to having the students in your school working on personal group projects, feel free to contact us, and we investigate the world together!