Detective Academy: Challenge 6

The Challenge

Make yourself into a sundial!

What is a sundial?

Sundials are the world's first clocks. They were used by many ancient societies like the Greeks, Romans and Egyptians. Sundials tell the time using the sun. When the sunlight hits the upright arm, it casts a shadow onto the ground. Where the shadow falls shows what time it is! This can be tricky though as the amount of sunlight we get can vary based on the season and the weather.

A tip! If it is smoky in your area, you can do this activity inside using an alternate source of light like a lamp or flashlight instead of the sun! In our example, Nicola used a lamp instead of the sun.


Step 1: Start off by finding a spot outside that doesn’t get shade at any point throughout the day. The spot also needs to be a hard surface like cement or brick. If you are doing this activity inside find a wall without any furniture against it to cast your shadow on to. 

Step 2

At the start of the day stand in your preferred spot. Use a piece of chalk to trace around your feet and make an outline. If you are doing this inside use a piece of tape instead of chalk. This will mark your place so you can get consistent readings!

Step 3

Take a photo of what your shadow looks like at the start of the day. Draw a line at the top of your shadow, or add tape to the wall so you can track the changes throughout the day! Write down the time next to your mark or on top of your tape.

Step 4

Later in the day, come back to your spot and put your feet back into their outline. See how your shadow has changed! Take another photo of what your shadow looks like. Draw another line with chalk at the top of your shadow. Write down the time!

If you are doing this inside, change the position of your light source to mimic the way the sunlight shifts throughout the day. Place a piece of tape at the top of your shadow, and write the time down on it.

Science Fun Fact!

Since the earth rotates around the sun, the direction and position of the sun in the sky changes throughout the day. You can see an example in this image from PBS. When you are moving your light source, you’ll want to make sure that you mimic the path of the sun. 

If you want to learn more or see a video of this process, check out the PBS webpage on the Changing Path of the Sun.

Back to our experiment! 

Final Step

A few hours later, come back and measure your shadow one more time. Compare your photos and markers to see how the length and position of your shadow has changed over the day depending on where the sun was in the sky. Now we can use the sun and our shadows to look at what time it is!

Looking for more?

We have other awesome detective academies challenges on the blog!

Detective Academy: Challenge 7

Detectives need to protect their research with a code. Sometimes they also need to decipher a code! This week we are going to learn how to decipher codes to be ready for any future missions.

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Detective Academy: Challenge 8

This week is our last detective academy! You have all done so amazing and are almost ready to become detectives. Our last challenge will sharpen our observation skills.

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