Who Is Moving: the Sun or Us?

We are learning to use a torch and a ball to show how Earth's spin makes day and night and makes the sun seem to cross the sky, and to start a shadow log that measures what the sun is doing.

Before you startAbout 60 minutes · what success looks like · notes for the helper

About 60 minutes. It's fine to stop after the Quick Check and come back another day: the lesson opens where you left it, at the Quick Check.

You'll know you've got it when

I can use a torch and a ball to show that Earth's rotation gives day and night, and explain why the sun seems to move from east to west when it is our town that is moving
I can work out solar noon for my town from a sunrise and sunset table, and explain why it is rarely 12:00 on the clock
I can set up a shadow stick, check it is upright with a string and weight, and record the length and direction of its shadow with units
I can write a prediction of how the noon shadow will change by winter, with a reason

For the helperhow to sit beside this lesson, and what this step is for

This step: Spark

Start with the question at the top and chat about it. There is no wrong answer here: it gets your learner thinking about what they already know.

Getting ready: A ball or an orange for Earth, a small sticker, an LED torch (the cool kind) and a room that can be darkened. For the shadow stick, a straight stick or garden stake that stands about 50 cm above the ground, a ruler or tape measure, a peg or stones to mark the spot, and a piece of string with a small weight tied on. For the solar noon sums and the Solar Noon Detective task, a sunrise and sunset table for your town (printed, in a newspaper, or from a government sunrise and sunset calculator). The whole lesson takes about 60 minutes, and setting up the stick and finding solar noon can easily stretch it into two sittings; the check is a natural place to break. One safety point worth keeping in view: nobody looks at the sun, even briefly or through sunglasses, because all of this unit's sun work is done with shadows.
What understanding sounds like: Listen for your child saying that the sun only looks as though it moves because our town is being carried round, and for them using the torch and ball to show it rather than just say it. Also listen for 'the shadow is shortest when the sun is highest', for solar noon being found halfway between sunrise and sunset, for the plumb line being used to check the stick and a length written with its unit, and for a winter prediction that comes with a 'because'.
A likely mix-up, and something that helps: The big one is that the sun travels around a still Earth, because that is exactly what it looks like. You might ask, 'If we were riding on a spinning ball, what would we see?' and let them show you with the torch and ball. A second is that noon on the clock is when the sun is highest; looking up your town's table together and noticing the gap usually settles it.
If it comes easily: For a quick finisher, there is a good puzzle in predicting which way the shadow will point at solar noon in July and in January (for most of Australia it is the same way both times) and why, or in working out solar noon for three dates a few months apart to see how much it drifts.
If it's a struggle: If it's a struggle, one way is to stay with the torch and ball only: let them point to the sticker at sunrise, midday, sunset and midnight and say 'lit' or 'dark' each time, before any times or numbers come in. The solar noon sums can wait for a second sitting. If your child does not want to go on, setting up the stick together and leaving the rest for another day is a real start, because the log runs all year.

Step 1 of 6 · Spark

Lesson 1 of 5 · Earth on the Move: Day, Night and the Year

Who is really moving?

For the helper

Start with the question at the top and chat about it. There is no wrong answer here: it gets your learner thinking about what they already know.

Go outside early one morning and stand beside a fence post or a tree. Its shadow stretches long across the ground. Come back at lunchtime and the shadow is a short, stubby puddle at its foot. Come back late in the afternoon and it is long again, but now it points the other way. Everything your eyes tell you says the same thing: the sun is the one doing the moving, climbing up one side of the sky and sliding down the other. For most of human history almost everybody agreed. So here is the puzzle for today. If you were riding on a giant spinning ball, what would the sun look like to you? And how could you tell a moving sun from a moving you?

Sunrise, midday, sunset. It looks as though the sun is travelling. Is it?