Energy, Bristlebots and Data in Ms. Mulcahy’s 4th Class

This month we have been learning about energy. Like all scientists, our discover began with a question. We used a concept cartoon to begin.

This concept cartoon helped us discuss how we thought cars moved and also introduced us to new vocabulary. The concept of energy was one we all knew but just didn’t have the vocabulary to explain. We all agreed the car had ran out of petrol but we also agreed that a car used this petrol to make the car move…. but how??

This began our exploration of energy. First Ms. Mulcahy explained that all things needed energy. The first kind of energy we tested was Potential Energy.

Every object which could move stores Potential Energy. Anthony shows us how a pogo stick has potential energy. Next we asked Anthony to bounce on the pogo stick to give it its next form of energy – Kinetic Energy. This is the energy an object has when it is moving. Next we looked back at the car and discussed what type of energy this had to get it moving. We decided that the petrol was a form of Chemical Energy. We also knew that a car must have some electrical energy as it had a motor. Next we needed to make sure we could distinguish between all of the different types of energy. We did this by sorting different objects into different categories.

Once everyone in the class was aware of the different kinds of energy a car needed to move, we decided we would like to test and design our own car. We made a list of all the things we would need to make our own car. Ms. Mulcahy gave us toothbrush heads to incorporate into our design. She told us these would act as the wheels.

We went through our equipment list and tried to link it to what a car would need to move. Each material we wrote on the board was also found in a car. Next we went about building and designing our Bristlebot. We spoke about the different type of energy which was created by our bristlebot.

  1. Potential Energy in the Bristlebot
  2. Chemical Energy in the battery
  3. Electrical Energy which carry the electrons through the wires from the negative side of the battery to turn on the motor
  4. Kinetic Energy when the bristlebot moves due to the vibration of the toothbrush heads
  5. Sound energy being created by this vibration

After our designing we had a look at our Scientific Method and discussed our hypothesis.

We know that a hypothesis is devised by making a sentence with: If….then…because. We again thought about a normal car and its movement. What happens to a car when we have lots of people in it versus a car with only one person inside. We decided that a car which carried more weight is more likely to be slower. Then we wrote the hypothesis we wanted to test:


Next was the test. We discussed fair testing and each group made a track which was the same length. Each group used a stop watch to time their bristlebot. We timed how long it took the bristlebot to get to to the end of the track with no coins, one coin, two coins, three coins and four coins. We noted the result in a graph form. We used a bar chart as we felt it was the clearest way to see our results. Have a look at our testing and some of our work.

We decided that our data supported our hypothesis, the added coins slowed our bristlebot down, much like more weight in a car. This meant the motor had to work harder.

We had a fantastic time learning about energy and working as scientists to test an independent variable. Hope you enjoyed reading about it as much as we did learning about it.

Post Author: Kimberly Mulcahy