Junkbots are fun, simple robots that you can make from recycled materials. You can use them to teach students about the engineering design process, various physics concepts, recycling, or just as a fun classroom activity. Neither you nor your students need any previous experience with building robots.
Ben Finio, PhD, Science Buddies
- For each student or small group of students building a robot, you will need these items from the Bristlebot Kit
(also available as a Classroom Kit specially priced for teachers):
- Motor (1)
- AA batteries (2)
- Battery pack (1)
- Note: Each kit contains enough parts for two Junkbots, as well as parts for two bristlebots.
- For the entire class, you will need:
- Assorted recycled materials (cardboard, clean plastic bottles, etcetera)
- Assorted craft materials (pipe cleaners, googly eyes, etcetera)
- Small Phillips head screwdrivers
- Optional: hot glue guns (adult supervision recommended for young students)
- Optional: hobby knives (adult supervision recommended for young students)
- Open floor space on a smooth surface (not carpet)
- Connect a simple circuit using a battery and a motor, and use it to power a simple robot.
- Use the engineering design process to design, build, and test a simple robot.
- Ask your students to bring in recyclable materials like cardboard and clean plastic bottles from home, or collect recyclables in your classroom.
- Set up bins or tables with all your materials organized by type. For example, all plastic in one bin, all cardboard in one bin, all craft/decoration materials in another bin.
- Set up a separate table with any tools that require adult supervision, like hot glue guns or hobby knives.
- Create an area of open floor space on a smooth surface (not carpet) for students to test their robots and have a free-play area.
- Use tape to mark start and finish lines a few feet apart for a "race course" on the floor.
- Use tape to make a circular "sumo wrestling ring" a few feet in diameter on the floor.
- Optional: use a small Phillips head screwdriver to remove the screws from the battery pack covers in advance. This will save time if you do not have enough screwdrivers for the whole class, or if you have younger students who may have trouble using the screwdrivers.
- Recommended: follow the instructions and build one robot yourself before you do the activity with your class. This will help you understand how the robots work and familiarize you with troubleshooting steps you may need to take with your students.
Recommended: walk the entire class through steps 1–9 together to connect the motor and battery pack, and make sure each student's circuit is working before proceeding. Then let students build and test their robots (steps 10–14) at their own pace.
- Make sure the battery pack's switch is in the OFF position.
- If it was not removed in advance, use a small Phillips head screwdriver to remove the screw on the battery pack's cover, then slide off the cover.
- Insert two AA batteries into the battery pack. The flat ends of the batteries should go up against the metal springs, and the "+" signs on the batteries should line up with the "+" signs in the pack. Younger students may need help with this step.
- Slide the cover back on until it clicks into place. You do not need to replace the screw.
- Tightly twist together the exposed metal parts of the red wires from the battery pack and motor. You should be able to gently tug on the wires without them coming apart. Younger students might need help with this step.
- Repeat step 5 for the black wires.
- Firmly press a cork onto the motor's shaft. Make sure the cork is off-center. This will make the motor vibrate.
- Make sure the exposed metal parts of the red and black wires are not touching each other. Then, hold the motor with one hand and turn the battery holder's switch to ON. The cork should spin and make the motor vibrate. If any students' motors do not spin, see the troubleshooting section to help them problem solve.
- Turn the battery pack's switch OFF. Now, use electrical tape to tightly wrap the exposed metal part of each set of wires. This will help prevent short circuits.
- Build a body for your robot out of recycled materials. There is no "right" or "wrong" way to build the robot's body. This is an open-ended design problem, and the pictures in this lesson plan are just examples. Make sure you plan where you will attach the motor and battery pack, and don't forget to decorate it!
- Attach the battery pack and motor to your robot's body. Pay attention to these tips:
- Make sure you do not glue or tape the battery pack shut, or make it too difficult to access. Eventually you will need to slide it open to replace the batteries.
- Make sure the cork can rotate completely without getting stuck against the robot's body.
- Make sure the wires will not get tangled in the cork when it spins.
Cork does not spin at all when battery pack is turned on.
The cork flies off the motor shaft when it spins.
- Check that batteries were inserted properly. Younger students may have trouble with this and insert one battery backwards, or not fully click the batteries into place.
- Check for short circuits. The exposed metal parts of the red and black wires should not touch each other. This can occur if students did not completely wrap the wire connections in tape.
- Make sure the cork can rotate freely without getting jammed against the robot's body, and that it is not held in place by too much glue or tape.
Robot stops working suddenly.
- Press the cork further onto the motor shaft using a new hole.
- Optionally, a small dab of hot glue placed in the hole can help hold the cork in place.
The cork spins, but robot does not move at all, or moves very slowly.
- Remove tape from the wires and make sure the metal parts are still twisted together. The motor's vibrations can cause the wires to come apart if they are not twisted tightly enough.
- If you have access to a soldering iron at your school, you can solder the wires together to strengthen the connections.
Several things can prevent a robot from moving or make it slow:
Robot does not go straight.
- There is too much friction between the robot and the ground. Try using a different material for its "feet."
- The robot is too heavy. Try removing some materials from the robot or using lighter materials.
- The motor is not firmly attached to the robot's body. This means the vibrations will not transfer from the motor to the robot's body. Try using more glue or tape to securely attach the motor to the robot, but make sure the cork can still spin.
- The robot's body is not stiff enough (for example, cardboard pieces held loosely together by tape). This can cause all the vibrations from the motor to be absorbed by the robot's body, instead of transferring to the ground and causing the robot to move. Make sure all the different parts of the robot's body are tightly taped or glued together.
- This is very common—since the robots are powered by vibrations, it is actually very difficult to make one that goes perfectly straight. So, do not consider this a problem—consider it a challenge for your students!
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45 minutes to 1 hour
45 minutes to 1 hour
Electrical circuits, friction, mass, recycling, engineering, problem solving
This lesson plan aligns to these NGSS standards:
This lesson plan aligns to these Florida standards:
This lesson plan aligns to these Texas standards: