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Activity (Hands-On)Grades 7 - 9

Beating the Motion Sensor

Materials List

Photo shows two caged lights and a sensor box.Figure 1. Motion-sensor, or security lighting, sold at most home improvement stores are typically PIR sensors.

Each group needs:

  • 1 toy LEGO® racer car (or other pre-made toy car that rolls smoothly across a table and is less than 6 inches long)
  • 1 disposable hand warmer (typically found at outdoor stores, pharmacies or online from large retailers)
  • 6 inch x 6 inch pieces of the following materials (purchased at hobby and/or hardware stores):1/16-inch thick aluminum, ceramic tile, 1/8-inch acrylic/Plexiglas, 1/8-inch wood veneer
  • 7 inch x 7 inch piece of fabric
  • 6-inch embroidery hoop (for fabric frame)
  • several lengths of masking tape
  • 8-10 wooden craft (Popsicle) sticks or plastic straws
  • Can You Trip It? Worksheet (PDF), one per person

Testing station(s) to share with the entire class:

  • 2 inch x 2 inch plywood square one per testing station (use 1/2-inch plywood so it is sturdy)
  • passive infrared sensor with a light bulb, preferably red (a PIR sensor is a motion sensor-controlled socket, see Figure 1; available in the lighting sections of home improvement stores)
  • (optional) ultrasonic motion sensor (ultrasonic sensors are typically used in commercial buildings, see Figure 2; available online for $50-100; if possible, purchase a sensor that is designed to mount to a wall, not a ceiling)
  • light socket with attached wiring and light bulb, preferably red (for use with the ultrasonic sensor)

Photo shows a light switch with a built-in motion sensor.Figure 2. A wall-mounted ultrasonic motion sensor detects room movement and controls lighting.