How to Implement

• Girls will work individually.
• As a whole group have a discussion about circuits.
  • Start by having girls share what they know about circuits. [Circuits need three things: source of power (battery), conductive materials for electricity to flow (wires), load (motor, lightbulb, buzzer, etc.)]
  • Batteries have both a negative and positive side. In a circuit the electricity flows from the positive side of the battery, into the red wire, through the motor, then out through the black wire and back into the negative side of the battery. [Circuit = circle of electricity]
  • Explain how the doodle bot will work. Tell the girls they are going to create a circuit with a vibrating motor. To make the motor vibrate, they will add a counterweight (offset weight) to the end of the motor. As the motor spins, the offset weight will make the whole motor wiggle. Can they think of something that has a vibrating motor? (cell phones!, video game controllers, toys, like hexbugs and lots of others)
  • The girls will attach their circuit (with wiggling motor) to a cup with markers attached to the bottom. As the motor wiggles, the markers will draw a design!
• Pass out materials
  • Show the girls how to put the circuit together, having them do each step with you.
  • Use wire strippers to strip the end of the battery pack wires so about 1 inch of wire is exposed. You can have the girls do this, or do it ahead of time yourself.
  • Attach one paper clip to one of the terminals on the bottom of the motor (one of the small metal pieces with a hole in it). Secure with electrical tape.
  • Attach one battery pack wire (either color) to the other terminal on the bottom of the motor. Make sure the metal wire loops through the hole in the terminal and is twisted back on itself so it has strong contact with the metal terminal on the motor (you don’t want the insulation to get in the way, which is why we strip the insulation from the end of the wire). Secure with electrical tape.
  • Attach a paper clip to the other wire of the battery pack. Secure with electrical tape, but leave most of the paper clip metal exposed.
  • Insert a battery into the battery pack. Look inside the battery pack to see which way the battery should go.
  • Test out the circuit by touching the two paperclips together (this is the switch!).
  • Warn girls with long hair to be careful that their hair doesn’t get tangled in the motor as it spins.
  • It may be hard to tell if the shaft on the end of the motor is spinning; feel it with your finger to make sure.
  • The motor won’t vibrate much yet. It’s good to have the girls notice this.
  • If the motor isn’t spinning at all when the paper clips touch, something is wrong with the circuit (a short circuit, or an incomplete circuit). Problem solve!
    • Check each connection.
    • Make sure the battery is correctly in the holder.
  • Attach the offset weight by poking the shaft of the motor into a mini-eraser.
    • Attaching to the center of the eraser will wiggle less.
    • Attaching nearer one edge of the eraser will wiggle the motor more.
  • Once everyone's circuit is working, have the girls attach their circuit to their cup. Give them freedom and time to come up with their own design, and let them experiment. The finished doodle bot should have the following things:
    • three markers attached to a cup (like legs, or a tripod)
    • battery pack attached to outside, inside, or top of cup with tape
    • motor attached anywhere on cup, but make sure that the eraser is able to spin
    • access to the paper clips, so they can still touch (this is how the circuit is turned on and off)
  • Encourage the girls to use lots of tape. Things will jiggle loose when they turn their vibrating circuit on.
  • Have them experiment to see which positions and attachment methods work best.
• Doodle! See what kind of art each doodle bot makes by taking the caps off the markers and turning circuits on (be careful that they don’t wiggle off the table).
• Decorate! If there is time, let them decorate their doodle bots with craft materials.
• Discuss:
  • What do you think makes the doodle bot move? (the weight of the eraser, the robot's center of gravity, creating vibration to move it across a table)
  • Observe the doodle bots in motion. Do they all move in the same way? Hypothesize why or why not.
    • What variables could you change to affect the way your doodle bot moves?
      • location of heavier parts: battery pack, motor
      • height/attachment of markers
      • position of the motor and/or eraser
  • What else could the doodle bot do with just a motor and battery? If there is time, have them test out their hypotheses.