When light hits an object it may:
- go straight through – the object is TRANSPARENT eg. glass window
- go partly through and scatter – the object is TRANSLUCENT eg. frosted glass
- be blocked – the object is OPAQUE eg a book
Light travels in a straight line so opaque objects will create shadows.
Playing with shadows on a sunny day is great fun. Exploring the changes in shadows over the course of a day can be very interesting.
Things you need:
- Sidewalk chalk in a variety of colours
- A sunny day
- Open concrete area that can be drawn on that will be in the sun all day
- Time in the morning, noon and afternoon.
- Remind students not to look directly at the sun!
- In the morning, working in pairs, trace the shadow of your partner onto the concrete.
- Include the outline of their feet so they can come back to the same spot.
- Write your initials and the time in the shadow space.
- Come back at noon. Stand on the same spot and re-draw your shadow using a different colour chalk.
- Come back again in the afternoon and re-draw your shadow again with a third colour.
- Compare your shadows. Take photos for later discussion.
Questions to ask:
What is creating our shadow?
Are all your shadows the same size and shape?
Do all your shadows point the same way?
What is different about them?
At what time of day was your shadow the biggest? At what time of day was your shadow the smallest? Why do you think that is?
Go outside on a cloudy day. Where is your shadow? How come?
Find other shadows outside e.g. birds flying overhead, shadows of trees, playground equipment, etc.
Put toys or furniture in the sunlight and trace the shadows. How do the shadows change if you turn the object? How do they change over the course of the day?
Can you find a way to make your shadow disappear?
Explore making different sized shadows indoors by changing the angle at which the light from a flashlight hits an object.
Science World British Columbia
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