Earth's rotation and day/night

Activities to try

1. 1

   Spin the Earth beside a fixed Sun — and watch the Sun 'rise'

   Why it works: The Sun did not move — YOU did. Turning the Earth is what makes the Sun appear to cross the sky, and night is simply your side facing away from the Sun, not the Sun hiding behind hills or clouds.

   1. In a darkened room, set up one strong lamp as a fixed Sun and a globe with your own location clearly marked with a sticker.
   2. Slowly rotate the globe yourself (don't just watch someone else) from west to east (anticlockwise when seen from above the North Pole), and track your marked spot as it sweeps from the dark side into the light and back out again.
   3. If using a screen model: drag to spin the Earth west to east next to the fixed Sun, with a 'you-are-here' pin that sweeps from the dark side into daylight, while a coupled ground-level view below shows the Sun rise in the east, climb to its highest point around midday, then sink and set in the west, in step with your spin.
   4. Say out loud, at the moment the Sun appears to rise in the ground view, what is actually moving — the Sun, or you?
2. 2

   Be the Earth: spin versus orbit

   Why it works: Spinning on the axis once a day makes the daily day-and-night cycle; orbiting the Sun once a year makes the year. These are two different motions and must not be conflated — the daily cycle depends on the spin, not on the orbit.

   1. Stand and spin slowly on the spot facing a lamp Sun: notice your front (day) and your back (night) — one full turn is one day and night, about 24 hours.
   2. Now, keeping facing the same direction in the room, walk a slow large loop around the lamp: this is the orbit, which takes a whole year (about 365 days).
   3. Describe in your own words: which motion causes day and night, and which causes the year?
   4. Try the wrong version deliberately — 'the Earth goes right round the Sun each day' — and explain why that is not what makes daytime and night-time: the real trip round the Sun takes about a year, but day and night repeat about every 24 hours.
   5. Now imagine the Earth stopped spinning but still travelled its yearly loop round the Sun: decide whether you would still get the normal daily day and night, and explain why or why not.
3. 3

   Elicit and confront: what causes night?

   Why it works: Surfacing your own starting idea and naming the specific wrong tracks makes it possible to notice exactly which one you held and to replace it with the rotation explanation.

   1. Before any teaching, answer the probe 'What causes day and night?' in your own words and sketch what you think.
   2. Compare your idea with the common wrong tracks: the Sun goes behind hills or clouds; the Moon covers the Sun; the Sun travels round the Earth once a day; the Earth loops the Sun once a day.
   3. After the globe and enactment work, revisit your first answer and mark what you would now change.
   4. Explain why, right now, it can be daytime where you are but night-time on the far side of the world — and why the Sun looks like it moves across the sky during the day.
   5. Answer in two steps — first what happens (day/night), then WHY — choosing from the real spin explanation and the documented alternatives (Sun behind hills; Sun orbiting Earth daily; Earth orbiting Sun daily; Moon/clouds covering the Sun).