Electricity - test for conductance

Use a circuit with a bulb to test whether various materials conduct electricity
Science content
Physics: Energy forms, Conservation of Energy (1, 3, 4, 5)
Physics: Electricity, Electromagnetism (7)
  • board to attach materials to e.g. cardboard covered in white paper and coated in wide clear tape
  • tape to attach materials to the board e.g. masking tape
  • battery (in battery holder easiest, but can have wires taped to the end of it)
  • bulb e.g. holiday light stripped out of its chain, or use a bulb in a holder
  • materials to test (e.g. nail, paper, coin, wood, plastic, key, styrofoam, pipe cleaner, electrical wire, pencil graphite), or wander the classroom with the board to test materials
  • additional lengths of wire to make the circuit larger - students can cut these themselves

Students build a circuit by taping the components to the board, initially with a battery and bulb, to test the circuit. The bulb should light when the circuit is closed (makes a loop).
Show them how to open the circuit up, so that they can place objects to test in the gap, to see if they conduct electricity (and therefore light the bulb). They may need to add an additional wire to make components reach.

Provide test materials, and also encourage students to walk around the classroom with their board, testing materials that they come across. (They may need to add in an additional wire so that their circuit can reach off the board for testing.)

Summarize together - metals conduct (that is why electrical wires are made of metal).
Plastic and styrofoam are insulators (that is why electrical wires are covered in plastic, and why we used a styrofoam base for our circuit).
Carbon also conducts.

For older students, materials conduct when they have free electrons that can move within the material to make a current.

Does water conduct? Try it. No. Why are we so concerned about electrical appliances in the bath? They are with much higher voltage, and it is only a problem if it goes across your heart.
Try other liquids, solutions of kitchen chemicals (baking soda, sugar, lemon juice, vinegar) - also see the electrolysis activity.

Grades taught
Gr K
Gr 1
Gr 2
Gr 3
Gr 7