## Childrens alternative ideas

Methods of teaching science which are based on the idea that pupils build up, or construct, ideas about their world are often called constructivist approaches. If we want pupils to understand and use scientific ideas their existing beliefs need to be challenged or extended. We cannot always replace these naive ideas, but we can encourage pupils to use the scientific ones when appropriate, and to show them the inconsistencies in many of their existing ideas. This chapter looks at ways to probe and display their ideas. In Chapters 6-11 we look at active learning approaches that allow pupils to reconstruct the scientific ideas we present to enable them to make them their own.

The small sample of questions given in Figures 5.1-5.12 have all been used in schools to probe children's understanding. They are very basic - indeed so simple that we might wonder how older pupils could ever answer them inappropriately. Before you read the commentary on the questions try to answer the questions yourself at your own level and then as you think a child may see them. Better still, try them out on small groups of pupils across the age and ability range. What alternative ideas did you predict and find? If you are trying them with children, it is best to have the actual materials with you - for example, for the first question use two blocks of ice and wrap one in a hand-towel.

The water in the toilet tank froze. Later that day someone put a blanket round the iced-up tank. Will this make the ice in the toilet tank melt:

FIGURE 5.1 Frozen tank (from Ross 1998, p. 70)

Predict the temperature of the water in each cup after either sharing or mixing: (i) When water at 60°C in a jar is shared (ii) When water at 10°C and 70°C from two between two cups cups is mixed

FIGURE 5.2 Temperature (after Stavey and Berkovitz 1980)

What is the function of the wick?

What is the function of the wax?

What is the function of the wick?

What is the function of the wax?

To hold what is burning

To slow the rate of burning

To burn -it's the fuel

(a) Wax and wick. Use the possible answers on the right to answer the two questions on the left.

(b) Condensation. If you hold a jam jar upside-down above a candle flame to collect the hot air, condensation collects on the inside of the jar. Where does this water come from? Note in contrast: if you aim the hot air from a hair drier into a dry jar, the jar will get hot but does not get damp.

FIGURE 5.3 Candle

Predict (and explain) any change in weight:

(i) To plasticine if you flatten it out.

(ii) To a sugar lump if you crush it and weigh all the bits.

(iii) To a glass of water if you add salt to the water then stir.

FIGURE 5.4 Weight

FIGURE 5.5 Football (multiple choice question in the form of a Concept Cartoon™ after Keogh and Naylor 2009)

What do you think?

FIGURE 5.6 Exhaust gas

What do you think?

FIGURE 5.6 Exhaust gas

For this you need a 1.5 V cell, a matching bulb and one piece of wire.

Can you make the bulb light using just the cell and a single piece of wire?

FIGURE 5.7 Cell and bulb

 person fire car cow daffodil tree fish whale j spider bird grass cabbage h cat seeds frog-spawn fly

• Sort the cards to show those that are alive, dead, never lived. Are there any left?

• Now sort the cards into animals or not animals.

• Now sort the cards into plants or not plants.

FIGURE 5.8 Living - plant - animal (after Osborne and Freyberg 1985, p. 30)

For this you need a 1.5 V cell, a matching bulb and one piece of wire.

Can you make the bulb light using just the cell and a single piece of wire?

FIGURE 5.7 Cell and bulb

FIGURE 5.9 Seeing (from Guesne 1985)

In order to see we need to open our eyes and we need a source of light. Draw lines to show how the light from the lamp helps us to see the book Use arrow heads to show the direction of the light.

FIGURE 5.9 Seeing (from Guesne 1985)

The children are standing on the Earth.

They are all holding stones. They let go of them. Draw lines to show where the stones all go.

FIGURE 5.10 Gravity (from Nussbaum 1985) R. Driver, E. Guesne and A. Tiberghien, Children's Ideas in Science, © 1985. Reproduced with the kind permission of Open University Press. All rights reserved.

Push from hand

Push from hand

Half-way up

Gravity

FIGURE 5.11 Force

At the top

Half-way up

Half-way down

### Gravity

A ball has been thrown up, away from the Earth. The first picture is the ball being pushed by your hand against gravity. The other three show the ball on its way up, at the top of its flight, and on its way down. For these three pictures, draw arrows to indicate the size and direction of any forces that you think are acting on the ball. The longer the arrow, the larger the force. Label the force(s) as we have done on the first example. Before you rush to answer this, consider what is happening to the speed of the ball - is it getting slower, or faster, or staying the same?

FIGURE 5.11 Force

They are discussing why adults don't get heavier and heavier even though they eat food every day.

They are discussing why adults don't get heavier and heavier even though they eat food every day.