
Homemade Sundial from a Paper Cup
Easy
Can you tell time using only the sun and a paper cup? A sundial works because the Earth's rotation makes shadows move in a steady pattern.
You build a sundial from a drinking cup with a straw and some pebbles. Point the straw north and set the cup on level ground in a sunny spot. Every hour from 10 a.m. to 3 p.m. you mark where the straw's shadow lands on the lid.
The next sunny day you read the shadow against your marks. Then you check how close your sundial comes to the actual time.
Hypothesis
The hypothesis is that the position of the sun can be used to tell time.
Method & Materials
You will make a sundial using a styrofoam cup, a straw, a compass, and other materials. You will then use the sundial to tell time.
You will need a styrofoam cup, a straw, a compass, a permanent marker, a pencil, tape, and some small pebbles.
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See what’s includedResults
After making the sundial, you can use it to tell time. You'll need to find a spot in the sun and use the compass to point the sundial north. Then, you'll mark the shadow of the straw on the cup lid every hour until 3 pm. The next day, you can compare the shadow to the marks to tell time.
Why do this project?
This science project is interesting because it teaches you how to tell time using the sun, just like people did hundreds of years ago.
Also Consider
Experiment variations to consider include using different materials to make the sundial, or using the sundial to tell time at different times of the day.
Full project details
Additional information and source material for this project are available below.Related video
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
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