Squishy Circuits
**Safety Note: The battery packs should never be shorted out (letting the wire/terminals touch each other directly). Our battery holders have safety features that prevent overheating, but with other battery holders they will quickly warm up and could cause burns if shorted. When doing any electrical project, batteries should never be shorted directly. LEDs should not be hooked directly to the battery pack terminals. They will burn out and may pop. LEDs require a resistor to limit the amount of power flowing through them. With Squishy Circuits, the conductive dough acts as the wire and a resistor, so they’re safe to use with the dough. Discussion Questions: 1. How can we create an electrical circuit using play dough? 2. Remind students the LED’s have two legs, one is longer than the other and the longer leg should go into the dough with the red wire. 3. What does it mean for a material to be conductive? Insulating? |
Circuit - Electricity flows in a loop called a circuit. A circuit starts and stops at the battery pack and flows through wires, conductive dough, and electrical components such as LEDs and motors.
Open Circuit - a circuit that is not complete. Electricity does not flow through an open circuit (home wall switch is open when the lights are off and is a closed circuit when you flip the switch and the lights are on) Short Circuit -These are circuits in which the electrons can simply bypass the LED and go through the conductive dough to close the circuit (takes a shortcut) LEDs (Light Emitting Diodes) – LEDs produce light from electrical power. To work, the LED has to be oriented properly (this is called polarity). Usually, the two leads are different lengths. The longer lead goes to the positive (red) side of the battery pack. The short lead goes to the negative (black) side of the battery pack. Conductor - Conductors are materials that allow electricity to flow through them. Most metals are good conductors. Insulator - Insulators are materials that do not allow electricity to flow through them. Air, plastic, rubber, and glass are good examples of insulators. Short Circuit - Electricity is like water; it takes the path of least resistance. It is easier for the electricity to flow through the conductive dough than through the LED (or other component), so if there is a path where the electricity can skip the LED and instead run through play dough the entire way, the majority of the current will do that. When this happens, the LED will stay unlit. This is called a short circuit. |
Procedures:
Build a Reading Fort at home using sheets, chairs, etc. Then use Squishy Circuits to create a light and doorbell for their reading fort!
- Take out materials (battery pack, conductive dough and LED’s)
- Create two small equal sized balls of dough and connect the battery terminals to the dough (one terminal to each ball of dough)
- Pull out one LED and look at the “legs” or terminals. Do you notice a difference? (one leg is longer than the other)
- The long leg should go into the dough with the red battery terminal, short with the black battery terminal
- Make sure the two balls of dough do not touch, this will create a short circuit and the light will not work
- Turn on the battery terminal, the light should come on, students can use multiple lights, instead of a ball they can roll the dough into two long cylinders to connect more lights
- Are you having a difficult time with the dough touching? What are possible solutions? Have you heard of insulators? Insulators do not allow electricity to flow through them.
- Have students purposely short circuit the light by touching the dough. Ask what they observed (they should notice that the light will go out but also that it will dim if there is some contact vs full contact). Now ask them to test different materials between the dough (plastic spoons, metal spoons, wood, cling wrap, straws, etc.)
- They should now be comfortable to experiment with circuitry.
- For advanced students, they can experiment with series and parallel circuits (See image above)
- Students will also use the switch and the buzzer to create a doorbell for their fort!