This is a good free play activity. See the Play-Debrief-Replay method of teaching in the resource.
Note: please read through about the short circuit possibility, and stop students before the battery and wire gets too hot.
Optional: if using homemade wires, make lengths of masking tape the width of the foil, and tape them next to each other to fill one side of the foil. Tear between the strips of tape, to make lengths of foil backed with tape. (See the 'Making home made wires' photos above.)
Show students their materials: battery, bulb, wires and tape.
Show students how to make circuits by taping wires and bulbs to their desk, making sure there is a good connection between the metals of each.
Optional for budding electricians: show students how to use wire cutters to clip bulbs from a holiday light string, strip the ends to expose the wires, then twist the wires together so that there are no single wires sticking out (thin single wires carrying all the current will heat up and possibly cause burns).
(For Ks show them how to build a simple circuit with two wires, a battery and a bulb, and allow all to succeed before adding more components.)
Start free play.
Note: watch for short circuits - if students bridge the ends of the battery with only a wire, there is no resistance in the circuit and more and more current will flow through the wire. This high current will make the wire and the battery heat up. Keep an eye out at all times and stop students from holding a short circuit configuration for more than a few seconds.
Once students have experimented for a while ask them to leave their materials, and gather to discuss what they find.
Discuss electricity concepts as students come up with them (see phenomena below).
Use circuit symbols to draw what the students describe.
Phenomena likely to come up, and terminology for them:
Short circuit When a battery is connected by a wire looping between both ends, with no bulb. The current can flow fast between the ends of the battery, until the wire and the battery gets hot. Do not let short circuits run for very long. (Buildings have circuit breakers to prevent short circuits from starting a fire.)
Lighting the bulb Students will find that they need to make a circle, containing a battery and a bulb to make the bulb light. Discuss that the electrons flow from one end of the battery (the negative) around the circuit and into the other end of the battery (the positive). If there is no circle, there will be no current and the bulb will not light. The incandescent bulb lights because as electrons squeeze through the thin filament inside the bulb, it heats up and gives off light (LED bulbs work differently). Students may experiment with number of batteries and numbers of bulbs. With incandescent bulbs they will light brighter and brighter as more batteries are added (+ end to - end in a row) until they eventually 'blow' (they do not actually shatter).
Blowing a bulb When enough batteries are connected (with the correct + and - orientation) they will blow a bulb (at least 7 batteries for my materials). When there is enough voltage, so much current is flowing through the filament of the bulb that it melts it, therefore breaking the circuit.
Series circuit A series circuit is when the battery and bulbs are all in a line, so that the electrons move through one component then the next. The energy (voltage) from the battery is divided between the bulbs, so the brightness of a bulb will depend on how many batteries and bulbs there are.
Switch Students will find that some bulbs go on and off as they move the wires around. A contact is not secure and so intermittently breaks the circuit. Real switches (e.g. light switches) break a circuit in a more controlled manner.
Parallel circuit When there is more than one path for the current to flow, most simply with two bulbs straddling one battery the energy from the battery splits and goes down both paths, before rejoining and returning to the battery. The brightness of the bulbs should be the same as when there is just one bulb, as each bulb will draw as much current as one alone when they are in parallel (unlike when they are in series).
Help students come up with new experiments to investigate more deeply (suggest students with similar questions work together).
If they have not already changed numbers of batteries and bulbs, encourage them to do so.
If they have not already made different shapes of circuits (series and parallel), encourage them to do so.
