Play-dough circuits for Christmas and all year round
Practical Activity for 5-11 11-14
To celebrate the end of term, why not get your class to build a festive circuit out of conductive play dough?
Although commercially available, it is cheaper to make your own dough before the lesson. This activity is about building a Christmas-tree circuit, but challenge your students to think about making conducting circuits in other seasonal/non-seasonal shapes or using other circuit components.
Apparatus and Materials
Materials required per group:
- Four AA batteries
- One battery pack to hold four AA batteries
- Six or more LEDs
- Cardboard (approximately 10 cm × 10 cm)
Health & Safety and Technical Notes
Divide the class into groups. The number of groups will depend on how much dough you have prepared. Introduce the activity by explaining that the added salt makes the green dough an electrical conductor. For older students you may also want to add that this is because sodium-chloride dissociates into charged sodium (Na+) and chlorine (Cl–) ions, meaning that the dough contains charged particles that are free to move.
Give each group two LEDs and ask them to investigate both series (see photo above) and parallel (see photo below) circuits. Discuss why an insulator (either cardboard or air) is needed between the layers of dough. Remind students that the LEDs will only light up if they are connected the right way around (i.e. the long arm of the LED is connected to positive).
Once they have familiarised themselves with building simple play-dough circuits, they should design and build their own Christmas tree with six or more working LED lights. Encourage them to think about which type of circuit is best (series or parallel) and how they will use the cardboard as an insulator to ensure that the LEDs will all work.
With thanks to the Squishy Circuits Project at St Thomas University, Minnesota, for permission to adapt their worksheet and reproduce their dough recipe. Visit their website for more classroom activities.
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