Summary 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) Lessons activity is in Electric circuits Properties of materials: sticky, stretchy, floating, long and strong Materials board to attach materials to e.g. cardboard covered in white paper and coated in wide clear tape, or tape circuit to desk 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 additional lengths of wire to make the circuit larger materials to test at table groups including metals and non-metals (e.g. nail, aluminum strip, copper strip, coin, key, electrical wire, string, paper, wood, plastic, styrofoam, pipe cleaner, painted metal e.g. ruler, pencil graphite or pencil sharpened at both ends (test before)) and/or wander the classroom with the board to test materials e.g. chair leg, plastic seat, pencil case items Procedure Students build a circuit by taping the components to the board, initially with just 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/or ask 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, styrofoam, string, paper, wood are insulators so does not conduct electricity. That is why electrical wires are covered in plastic. A pipecleaner conducts if the wires are attached to the metal inside at each end (but not via the fluffy plastic coating). Paint is an insulator, so metal objects that are painted may surprisingly not conduct electricity. Carbon conducts, although not as well as metals. A pencil sharpened on both ends (wires attached to the graphite at each end) should dimly light the bulb. Note that if the graphite inside is broken (from the pencil being dropped) there will be a gap and the circuit will not be complete. For older students: materials conduct when they have free electrons that can move within the material to make a current. Metals have these free electrons, shared among the metal atoms. 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
