The spring equinox marks the first day of spring and the steady lengthening of daylight hours, making it the perfect occasion to review concepts such as units of time and the Earth’s rotation. Looking for an interesting project to demonstrate how light moves as the sun’s position changes? Make a sundial!
For this activity, you need the following materials:
- A paper plate (or a large circle cut from cardboard)
- A pencil (or a straw, chopstick, or skewer)
- A marker or pen
- A pointy object (such as a well-sharpened pencil)
- A compass or compass app (optional)
- A watch
- Rocks to keep the sundial in place (optional)
Start by finding a good spot in the schoolyard for your experiment. If you can, begin the activity just before noon.
Stick the pencil (or straw) through the centre of the plate. Tilt the pencil slightly so that it casts a shadow pointing north.
Have the students check which way is north by using a compass, if you have one, or a compass app on your phone.
Weigh the sundial down with rocks if necessary to keep it in place. Come back at 1 p.m. and have your students write the number 1 at the spot on the edge of the plate that the pencil’s shadow is pointing to.
After the activity, you can ask your students to describe what happened. For example:
- How did the length of the shadow change as the sun moved across the sky?
- In which direction did the shadow move on the plate?
- Why does the sun seem to move across the sky?
- Etc.