QUIRKS in the WORKS

Key Stage 2

INTRODUCTION

Quirks in the Works is based on the sections on electricity of Attainment Target 4 of the National Curriculum for Science. We aim to make the scientific content self-explanatory but these notes will give you a guide to the topics covered so that preparatory and follow-up work can be done.

Our story follows two electrons, Fizz and Whizz, as they battle round a circuit in a smoke alarm. Along the way they encounter circuit diagrams, simple and parallel circuits, a resistor and conductors and insulators as they fight against the evil Dr No Go to sound the alarm.

SCIENTIFIC CONCEPTS EXPLORED

HOW ELECTRICITY WORKS

In a battery you have a positive and a negative end and, as electrons have a negative charge they are attracted to the positive side of the battery. This flow of electrons is what gives us electricity. The children are taught that Electricity is the flow of electrons.

ELECTRIC CIRCUITS AND DIAGRAMS

We move on to the electrical circuit. With the help of two members of the audience we demonstrate that you need a complete circuit for an electrical appliance to work, and we introduce a simple circuit diagram as a way of representing an electrical circuit:

Later in the play other symbols are introduced:

The children are taught and asked to remember ‘complete circuit - that’ll work it’

SERIES AND PARALLEL CIRCUITS

Our two electrons travel from the negative side of the battery along the wire until they come to a junction. Whizz realises that they must be in a parallel circuit. We then explain that there are two types of circuit: a series and a parallel.

In a series circuit everything is wired in a series (sic), one after another. If you were to add light bulbs to a series circuit each time another was added they would all become dimmer as they all share the same amount of current. When one light bulb blows all the others will go out as the circuit is then broken. We see this most frequently in Christmas tree lights, which are often wired in a series because they are not required to shine brightly and will not work at all if one bulb blows.

In a parallel circuit the electrical devices are wired one above the other, on separate wires. This means that there is more than one path for the electricity to flow through to get back to the battery. If light bulbs are wired in parallel, however many are added to the circuit, they will all shine as brightly as ever. This is due to the fact that more electricity is drawn from the battery every time another bulb is added and of course, if one bulb blows, the remaining bulbs will stay lit. Our house lights are wired in parallel to enable us to turn each light on and off without affecting the other lights.

The children learn that in a series circuit there’s just one way, in a parallel several routes will do OK

RESISTORS

Our electrons, now in a parallel circuit, split up when the wires divide and we follow Whizz as she travels around her side of the circuit. She suddenly encounters a strange new symbol on her circuit diagram, that of a resistor, and suddenly the resistor itself appears. She is lured in after realising that she has no choice but to go through the resistor to get back to the battery.

An explanation of resistors uses the analogy of a traffic warden controlling the flow of traffic. Sometimes the traffic can flow freely and at other times it is at a standstill, or moves very slowly.

Resistors are used to vary the current through a wire. Every material has an electrical resistance. The greater the resistance the smaller the current that flows through it. When a current flows through a wire, electrical energy is changed to heat energy and this principle is used in making heating elements for electric kettles and fires. The elements are made from a resistant material, such as nichrome, which, when electricity is pushed through causes a great deal of heat to be given off.

Resistors are used to control the flow of a current through a wire and variable resistors, as their name implies, can vary the amount of electricity flowing through a circuit.

The children learn that resistors block electrons.

CONDUCTORS AND INSULATORS

A gap has been made in the wire and our other electron, Fizz, cannot complete his side of the circuit.

He needs a conductor, but does not realise his piece of copper is just what he’s looking for. It takes the Undercurrent Resistance to come and rescue him and explain what conductors and insulators are before he can finally continue on his journey.

A conductor is a substance which allows electricity to flow through it. An insulator is a substance which does not allow electricity to flow through it. Metals are conductors and non-metals are insulators (except for carbon which is an important non-metal conductor. We do not discuss carbon in the play).

In general conductors are used to carry current - the wires carrying the electricity in our homes are usually made of copper, an excellent conductor. Insulators are used for safety and that is why plugs and wires are covered with insulators like rubber or plastic.

Good conductors include: copper, iron, silver, tin, aluminium, gold, mercury, carbon.

Good insulators include: plastic, wood, wool, paper, glass, string, nylon, rubber, air.

Strictly speaking, however, all substances conduct to some extent but most non-metals have such high resistances that they only carry very small currents. In fact, the currents carried by non-metals are normally so low that they can be ignored.

The children learn that conductors let the electricity flow. Insulators say ‘no no!’.

THE SMOKE SENSOR

At the smoke sensor Fizz explains how it works with the help of the audience.

The smoke sensor uses a special type of resistor which is light sensitive (a light dependent resistor). This type of resistor will not let electricity flow unless a light beam is shining on it which then reduces the resistance. In a smoke alarm the light beam does not shine directly on the sensor until smoke is present. The density of the smoke reflects the light beam onto the sensor which reduces the resistance letting the electricity flow through and the alarm to be sounded.

AT THE END OF THE PLAY

These are the areas of study covered in the show. At the end of the performance the actors will be happy to take questions.

THINGS TO TRY IN CLASS

Experiment to test conductivity.

Wire up the above circuit. Now try testing various substances to see whether they are conductors or insulators by clipping them across the gap. If the bulb lights up the substance is a conductor. If not it is an insulator. Try using a wooden spoon, a plastic ruler, kitchen foil, a piece of string, a coin, a knife blade, your jersey, cork and a paper clip. Draw up a table of your findings.

Experiment with series and parallel circuits

Wire up a simple circuit, using a battery, connecting wires and a light bulb. Try adding another light bulb and then another. What happens to the brightness? Remove the bulb from one of the lights. What happens then?

Wire up a parallel circuit, using a battery, connecting wires and two light bulbs wired one above the other. Add another branch to the wire and another bulb to the branch. What happens to the brightness of all three bulbs? Remove the bulb from one of the lights. What happens to the other bulbs?

Show Requirements

The actors will be arriving approximately forty minutes prior to the start time in order to set up and will need to have access to the school hall from then. They bring the set, lighting and sound equipment with them so only need access to a plug socket. They’ll need a space approximately 15’ wide by 10’ deep with the children sitting in front, either seated or on the floor. The show works well ‘on the flat’ but if it’s more convenient for the actors to use your stage, please let them know on arrival. Quirks in the Works lasts one hour with a two minute ‘q & a’ session at the end.