Exploring Motion

The students had some time to play with the motion detectors in an open-ended way for about 15 minutes. I heard the students make some interesting comments as they became acquainted with the detectors:

• One group believed that when they set the motion detector on its back (so that it was pointed towards the ceiling lights), the detector was sensing the light. Their graph even showed motion, but I pointed out that it was probably due to the fact that one of them was pushing the “Trigger” button on the front of the detector to start and stop the graph, and that the sensor was simply seeing the movement of her finger. It is interesting to watch them shift their knowledge from the light sensors to the motion detectors. Even though they were told they would be observing motion using the motion detectors, they still believed that light was affecting their graph in some way.
  

• Another group thought their motion detector was being affected by the sound in the room. They were making noises as they hit things on the table in front of the detector. I asked them to wave their hands silently in front of the detector to see if it could still observe some sort of motion without sound.
  

Using the motion detectors, the students graphed the motion of:

• Standing still
  
• Moving away, slow speed
  
• Moving away, fast speed
  
• Moving away, speeding up