(I'm participating in the "Classroom Science Contest" of Instructables. If you like my project, your vote will be highly appreciated!)
Hello. My name is Mario and I am a Colombian STEAM teacher in Azerbaijan.
My education center organized a Summer Camp, and "Design with 3D pen" was included in the curriculum. My original idea for the first lesson was: kids create a nice car using the 3D pen. The car rolls. Everybody is happy. Lunch time.
However, I learned about Michelin's 3D printed airless tires and their visionary concept tire and I decided to upgrade the activity: what about a race cars competition to define who created the best 3D printed wheels? Most of the kids love race cars, especially in Azerbaijan, where Formula 1 is the most important event of the year, and families and tourists come to see their favorite teams competing in the streets of Baku; so creating a racetrack would bring a lot of excitement to the classroom.
But, how to release all cars at the same time? what if two cars arrive to the finish line and it's not clear who the winner is? How could we integrate more concepts to this activity?
In this instructable you will learn how to create a 4-lanes racetrack. The racetrack has a release system at top. Cars will move thanks to the effect of gravity. At the end of each track, there will be a touch sensor wired to a Makey Makey. Makey Makey will send the arrival information to a Scratch 3.0 program, that will calculate the time that each car required to arrive to the finish line.
Don't worry about the materials! You can build the track using supplies from any hardware store. Also, the touch sensors were made from trash. Even I built all this system using junk from our depot. The only high technology pieces you will need are a Makey Makey and a laptop with Scratch 3.0 installed. And if you don't have 3D pens, there is no problem! This activity can be done with Hot Wheels cars, 3D printed cars, wooden cars or any rolling vehicle as long as they don't exceed the dimensions of the release area and the track.
Concepts explored during this activity: you can cover several STEAM fields in this exercise:
- Science: Physics concepts like gravity, traction, friction, forces applied over an object in motion, acceleration; and depending of how your students will build their cars, properties of different materials.
- Technology: kids will understand how a sensor can detect or measure a physical property. Also, they can explore how sensors are connected to a Makey Makey board that collects the input information and send it to a Scratch program coded to analyze and display the collected data.
- Engineering: Kids will explore simple machines like inclined plane, levers, wheel and axle. Also, they will have to apply the Engineering Design Process (Ask, Brainstorm, Design, Build, Test and Improve) to create their best car.
- Arts: using 3D pen (or the materials and tools of your choice), kids will design and customize their own race car.
- Mathematics: using the data collected by the sensors and Makey Makey, and measuring the racetrack and the cars, kids can calculate speed and acceleration of their car during the race. Also, they can be challenged to create a better Scratch program to calculate the time and display other interesting information about the race.
Time intensity: you can adjust this lesson according to your time and resources availability, and number of students. This lesson was completed in 2 hours for a group of 30 kids, focusing only in the car design and building, and test in the race track. However, my suggestion is to extend this activity to 4 lessons of 1.5 hours, distributed in this way:
- Car design: using 3D pen, CAD or assorted materials (bottle caps, bamboo sticks, cardboard, straws)
- Sensor construction: students learn how to build the basic touch sensor used in this activity, and test its sensitivity.
- Coding: kids learn how to create the basic program with Scratch 3.0, and they are challenged to make a better program to measure time and results.
- Testing and mathematical extension: kids are challenged to compete in the racetrack, and use math to calculate who has the fastest car.
Age group:this activity is more suitable for kids age 10 to 14 years old. I tested this lesson with 100 kids, distributed in 4 groups of 25 students: two groups in the 6 to 10 years old range, and two in the 11 to 14 years old range. If well all of them enjoyed the race, the younger groups struggled more trying to create a functional car and were not too interested in the data displayed by the computer. However, results may vary with classrooms of less kids and if design with 3D pens is changed for building with assorted materials. Also, this track can be used for older students to test cars made using CAD/CAM.
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Step 1: Materials and Tools
To build the racetrack, you will need the following supplies:
- 4 segments of gutter reference Classic120, of 1.5 meters each. Actually, these ones came in segments of 3 meters each one, so I cut them in half.
- 4 step ends for gutter reference Classic 120. Actually, references may change, so you can pick up any suitable gutter and compatible stop ends from your favorite hardware store.
- Wood strips
- Metal angles
- Assorted screws, nuts, bolts and washers.
- Long plastic beams. I found these red ones near the trash of a copying center, so it's uncertain where to get more. However, you can replace them with wood sticks.
- 8 CDs
- Large circular plastic caps. Originally, I used 4 green ones from gel pots and 4 red ones from water carafes. However, I had to improve the sensor, so at the end I only used the green ones.
- Metal bracket with hole on each end: I started using two per sensor. However, I finished using only one.
- 2 M4X6 bolts
- 1 M4X14 bolt
- 1 M4X16 bolt
- 5 M4 nuts
- Aluminum foil tape (like this one)
- Wires of different colors
DATA COLLECTION AND ANALYSIS:
- 1 SPDT Micro switch (like this one). This will be installed in the release system to send a signal to the Makey Makey to start the chronometer.
- 1 Makey Makey board with accesories
- Cables and connectors of different colors
- 1 plastic box to protect the Makey Makey
- 1 laptop with Scratch 3.0 installed
OTHER REQUIRED SUPPLIES:
- Hot glue
- Super glue
- Isolating tape
- Soldering tin
- Materials for your race cars (I will talk about this part later)
- Dremel rotary tool
- Soldering iron
- Leatherman multitool
- Measuring tape
Step 2: Basic Racetrack
Take a wood strip, cut it in a 56 cm segment and use sandpaper to make it smoother. Attach the gutter stop ends to it, using screws. When you have the for stop ends attached, insert the gutters on them.
Then, cut two 46 cm segments and attach them below the gutters. Screws must be attached in a position that doesn't interfere with the cars when they are racing. Best positions: at the end of the track and in the release system area.
Step 3: Elevation
This support creates a 35° angle between the racetrack and the table, providing the acceleration by gravity required to make our cars move.
Make a rectangle using wood strips (2 of 25 cm and 2 of 46 cm), iron angles and screws.
Attach 2 or 3 hinges to the 46 cm strip near the release system. Then, attach the rectangle to the hinges.
NOTE: This angle should be enough for cars with almost perfectly circular wheels. However, wheels made with 3D pens are not that accurate, so I had to use a container bin to elevate the track to 45°.
Step 4: Car Release System
Using hot glue, stick together pairs of CDs to increase their resistance. When your four "super CDs" are ready, check if they fit loosely in the gutters. If not, use the Dremel to cut the borders.
Stick the CDs to one of the red plastic sticks, using hot glue or any other kind of temporary glue. After checking they fit in the track, attach the CDs permanently using screws. The blue isolating tape I put over the CDs reduce the risk of shattering if you screw too much.
Now, place two 32 cm plastic sticks to each end of the previous building. They will be the levers that lift the CDs and release the cars.
Attach the system to the racetrack using nuts, bolts and washers.
Step 5: Touch Sensors (Part 1)
So, how this sensor works? It's basically a switch. The metal brackets act as contacts. In normal conditions, both contacts are separated by a distance of 1 mm. In the moment something touch the red plastic cap, the distance becomes 0, both brackets are in contact, the circuit is closed and the electric signal is send to the Makey Makey.
NOTE: In theory, this sensor worked perfectly, so I built four of them and I attached them to the end of the tracks. But I made a little mistake: I didn't test them with the real weight of the car. It turns out that cars made with 3D pens are very light, and they are not heavy enough to close the circuit.
I'm leaving these photos here in case your cars are heavier or for another application. I loved the design, and if well they didn't work as intended, I know they still can be useful and it's part of the Engineering Design Process!
How did I solve the problem of the sensors? Check Step 10.
Step 6: Installing the Sensors
Now, let's suppose our sensors are working fine and you tested them using a prototype of the car your students will create during the lesson. Attach each sensor to the stop ends of the gutters. If you use screws or bolts, check that they don't affect the sensitivity of the sensor.
Step 7: Wiring the Makey Makey (Part 1)
Each sensor has wires of a different color. Also, each track will be identified with a letter. That's by design, so you can identify where to connect each cable in the Makey Makey.
Track A: Down Arrow (White wires)
Track B: Left Arrow (Green wires)
Track C: Up Arrow (Red wires)
Track D: Right Arrow (Yellow wires)
Each sensor has two wires. Leave free one of them, so it can be connected to their respective arrow. Connect the other wires among them so they can be connected to the Earth port of the Makey Makey.
Don't forget to put the Makey Makey inside a protective plastic box, to avoid broken pins and accidental disconnections.
Step 8: Wiring the Makey Makey (Part 2)
Now, there is a fifth sensor you must connect to the Makey Makey. It's the SPDT micro switch. It must be attached under the release system. Before the race, the release system presses the switch to keep the circuit open. When the release system is open, the switch is released and the circuit is closed, sending the "Race started, reset timer" signal to the Makey Makey. Don't forget to connect one wire to the "space bar", and the other wire to "earth".
Release System (Micro switch): Space Bar (Black cable)
Step 9: Chronometer Code
This is a basic Scratch 3.0 program to measure the time between the switch activated by the Release System and the moment each car touched its respective sensor. You can challenge your students to create a better program! This code was also shared in the Scratch community.
IMPROVEMENT OPPORTUNITY: One little annoyance of this project is that as soon as you open the release system and cars start racing, you must close the release system again. If not, the switch will keep sending the signal of "reset chronometer". This brings a 1-2 seconds error to the experiment. If you can suggest a better code or solution so the program ignores the following "reset chronometer" signals after the first one, it will be very welcome!
Step 10: Touch Sensors (Part 2)
So I brought the racetrack from my workshop at home to our STEAM center, only to realize the sensors were not working as expected. Bringing the racetrack home was not an option, because is too long and bulky and it barely fits in the taxi. Also, time was running, and our Summer Camp would start in a few days. I had to solve the problem with the materials I had at hand.
Enter the aluminum foil tape. It's conductive and, being composed of aluminum foil and paper, it can be pressed by any small force and return to its original position after the car is removed. So I replaced the red plastic cap part of the sensor for this tape.
Step 11: Test and Improvement of the Track
The racetrack was tested using four different types of cars: two made with 3D pen and other materials, one made of Lego and one Matchbox toy car. Using cars of different weights helped to confirm if the program was giving less time to the car that arrived first to the finish line.
Step 12: Designing and Building the Car
To build the race car, kids can follow the template (I used Tinkercad to design it, I took a screenshot and copied it to Word), and then attach the pieces, or create their own idea. Additional materials for their cars can be craft sticks, bamboo skewers, straws and scissors.
Kids can use the formula Speed = distance/time to calculate how fast was their car and determinate who has the fastest car.
Now it depends on you! You have race track connected to a computer and several kids excited to test their race cars. Probably several of their designs will fail, and it will be your task to encourage them to improve their creations until they get the best Formula 1 car of the classroom!
First Prize in the
Classroom Science Contest