Electricity

Electrical energy - part 2

Current electricity

In the middle and senior classes children should have opportunities to construct circuits with batteries, wires, and components such as bulbs, switches and motors. They will discover how to make bulbs light and make switches and motors work. Investigations with electricity will provide many opportunities for activities with a technological focus. Children will design and make a variety of their own switches, using different materials and for different purposes.

Children in the senior classes will be guided to investigate how to make circuits using series and parallel wiring. In a series circuit the electricity flows through each bulb or component. When one bulb is removed the circuit is broken and all the lights go out. Children may discover that the more bulbs that are added to the series circuit the dimmer the light from each bulb becomes.

In a parallel circuit each bulb has its own circuit to the battery. If one of the bulbs in a parallel circuit is removed, no other light or component will be affected. When bulbs are in a parallel circuit each of the bulbs receives the same flow of electricity from the battery. Therefore the bulbs are equally bright.

When children have succeeded in lighting bulbs in series and parallel circuits they should be prompted to investigate the following questions:

Which circuit produces the brightest lights?
What happens if one bulb is removed from each circuit?
How long does a battery last in a series circuit and in a parallel circuit?

Conductors, insulators and switches

Conductors are materials that allow electric current to pass through them. Metals are the best conductors of electricity and are used for electric wires. Rubber, plastic, glass, cloth and other non-metallic materials are poor conductors. This explains why appliance plugs and electric wires are covered with rubber or plastic

Children should investigate materials that allow electricity to pass through them. They should make simple on-off switches. Older children can make two way switches.

Electromagnetism

In the senior classes children will explore how electricity and magnetism work together. They will discover that when a current passes through a coil of wire, the coil acts like a magnet. Exemplar 28 illustrates how a lesson on electromagnetism may be structured and how children can investigate the factors that affect the strength of an electromagnet.