Careful observation is the basis

Wrong Track: The sun rises and sets.

Right Lines: The earth spins, which makes the the Sun appear to change its position over a day.

Correct approaches and unhelpful starting points

Thinking about the learning

Our everyday speech and many myths and conventional drawings mislead us into thinking that we live on a stationary Earth, and that everything moves around that.

Thinking about the teaching

Making careful observations is the key. Not only of the Sun, but even sitting watching the moon for an evening, against some conveniently place power lines.

Living on a large sphere

Wrong Track: The Earth looks pretty flat to me.

Wrong Track: If the Earth is a sphere, why don't people underneath drop off?

Right Lines: The earth is a large sphere. Being pulled down is different for different continents. The pull is always to the centre of the Earth. This is due to gravity.

Flat and round

Thinking about the learning

Children generally like to believe adults and so it is not uncommon for them to amalgamate their flat Earth model with adults' spherical Earth model. Here are some ways in which they retain a flat Earth model and still build in roundness.

Common unhelpful ideas about the Earth

Thinking about the teaching

You'll need to explore the idea that the Earth is spherical explicitly, drawing on the children's ideas to challenge and develop theier views.

Common unhelpful approaches

Wrong Track: We get day and night so that we can sleep at night and do things in the day.

Wrong Track: It is when the Moon gets in front of the Sun and stops us getting sunlight and we call that night and then it moves and gives us the sunlight and we call that day.

Wrong Track: The Sun lights up the Earth so the Earth is shining brightly. It comes over the hills and mountains and when it starts to get dark the Sun goes back behind the hills and mountains.

Wrong Track: Because at night it isn't so warm and maybe the Sun goes behind a cloud.

Wrong Track: When the Sun comes to our side of the Earth, then it's day time.

Wrong Track: The Earth goes around the Sun every day. When it faces the Sun it's day.

Getting off along the right lines – a spinning Earth

Right Lines: The Earth spins on its axis, completing one turn a day. Day time for you is when your side faces the Sun.

Correct approaches and unhelpful starting points

Thinking about the learning

A reference to everyday life: We get day and night so that we can sleep at night and do things in the day.

Simple blocking explanations: These explanations all involve something getting in the way of the Sun, blocking its light and thereby creating the darkness of night. Common wrong tracks include arguing that the Moon, clouds or hills and mountains cause sunlight to be blocked.

Sun orbiting the Earth: Here the Earth is stationary and the Sun is in an orbit around it. According to this view, day-time comes when the Sun is on your side of the Earth and night-time when it is on the opposite side. For this model to work the Sun must orbit the Earth once a day.

Earth orbiting the Sun: Here the Sun is stationary and the Earth is in orbit around it. According to this view, day-time comes when your side of the Earth faces towards the Sun and night-time when it faces away from the Sun. It's the orbiting of the Earth around the Sun that is used here to explain day and night. For this model to work, the Earth must orbit the Sun once per day and also maintain the same orientation (facing the same way) in space, with no spinning. Here is a caricature of this suggestion.

download clip to view

Thinking about the teaching

Here the Earth is spinning on its axis in front of the Sun, once every 24 hours. According to this view, day-time comes when your side of the Earth is facing towards the Sun and night-time when it faces away from the Sun. Here is a caricature of the model.

download clip to view

Pupils' responses

Thinking about the teaching

There is an important progression in understanding here. For pupils to appreciate that the Earth is spinning, and that this is the cause of day and night, is a major step and suggests a more sophisticated understanding which you can build on.

Here are some responses from a mixed ability science class of 11-year-olds, before the year's work on the solar system, in a well established, rural comprehensive school to the challenge:

Teacher: Use words and diagrams to explain your ideas about why we get day and night.

These results suggest that it is worth probing your pupils' understanding of day and night right at the start of the teaching.

You might simply ask pupils to respond to the question:

Teacher: Why do we get day and night?

Alternatively you may wish to use a diagnostic question which actually confronts the pupils with possible alternative views and probes the link between ideas and evidence.

Rotating and orbiting

When describing the motion of the Earth, be very careful to distinguish between:

• The spin or rotation of the Earth, on its own axis.
• The orbiting of the Earth around the Sun.

Pupils tend to confuse these terms and may talk about the Earth spinning around the Sun once in a year. You will need to emphasise the difference in meaning of spin and orbit in your teaching.

download clip to view

Teacher Tip: Are we looking at spinning or orbiting here?

Visible during the day and at night

Wrong Track: The Sun is in the sky here in the daytime and the Moon is the night sky in Australia; then they swap so the Sun goes from here to Australia for their day and the Moon comes here for our night

A true story

A teacher was working with her Key Stage 1 class on this topic and asked them what they thought. All the children agreed with the statement above.

The next week, the Moon was in the morning sky and the teacher took them to the classroom window to see it. The children were totally bemused that what they had thought was not right – so much so that a few were really worried and one even asked: Are we going to die?

Thinking about the learning

We think that it is important to find out what children think and then allow them to make observations to test out their ideas.

By the nature of the topic, it is hard to find linked practical work in this topic so questioning to promote thinking and discussion between children, combined with acting-out and making representations will be focii.

On average, there's not much in the universe

Wrong Track: The universe is rather full of solid objects, much like around here.

Right Lines: The universe is mostly empty space, containing large, well-separated objects.

A few molecules in each cubic metre

Thinking about the learning

Children tend to have a very crowded view of space and this is not helped by the various diagrams of the Solar System that can be found on the internet. In order to see all the planets in one diagram, it has to be grossly out of scale.

Thinking about the teaching

You'll want to do some explicit modelling of the scales and distances to counter the distortions of the diagrams, and our everyday expectations which suggest that (local) space is rather full of things.

Staying in orbit

Wrong Track: Something must keep satellites up in the air, they can't just float in space, they're big heavy things. I mean aeroplanes have jet engines and wings to keep them up.

Right Lines: The satellite is taken up to its orbital height on a carrier rocket and directed out along its orbit, at a specific speed, with a rocket thrust. This speed is such that the gravitational force, at that height above the Earth, provides the centripetal force needed to keep the satellite in its orbital path. If the satellite is sent out into its orbit too slowly, it will fall to Earth. If it is sent out too quickly, the gravitational force will not be big enough to hold the satellite in orbit and it will fly off into space. Nothing keeps the satellite up. It is just a matter of setting the speed of the satellite such that the gravitational pull of the Earth (at the given height) tugs it around in its orbit.

Use a thought experiment

Thinking about the teaching

You might try using Newton's thought experiment, of throwing a ball into orbit from a huge mountain to transfer this idea that the satellite is continuously falling towards the Earth and nothing is needed to keep it up.

Circular motion

Wrong Track: Something must keep satellites going. Don't they have rockets which push them around their orbit?

Right Lines: Once the satellite has been accelerated into its orbit by a rocket thrust, it continues along that orbit, being tugged into its path by the gravitational pull of the Earth. In empty space the satellite would neither speed up nor slow down, but would keep travelling along its orbit forever. In low satellite orbits where there is a thin atmosphere, the air creates a drag and slows down the satellite. In such cases there is the need for occasional rocket thrusts to maintain the motion of the orbiting satellite.