Interpret Data Showing How Shadows Change

We’ve learnt lots about shadows, so let’s recap!

Can you remember what three things are needed to create a clear shadow?

 

 

-   A light source

-   An opaque object (to block the light)

-   A surface (to shine the light on and project the shadow onto)

 

 

That was nice and easy! Now, can you remember what affects the size and length of shadows each day?

 

 

The Earth is moving around the Sun, and it is this movement that makes the Sun appear to move across our sky.

This movement changes shadows throughout the day. When the Sun is low in the sky and rising, shadows of objects will appear longer, in the opposite direction to the light source (Sun). Since the Sun rises in the east, shadows will appear on the west side of objects in the morning.

 

 

These shadows will appear longer earlier in the day and get shorter as we reach midday.

 

With the basketball below, the Sun is rising in the east (which is on the left of the ball in this picture). The ball's shadow is therefore on the opposite side, which is the west (the right of the ball in this picture).

 

 

When it reaches midday, the Sun is high above us which causes much smaller, fatter shadows that will appear right underneath or behind objects.

 

Then, as the Sun begins to set in the west, the shadows start to grow longer again as the Sun moves to a lower and further away angle, creating shadows on the east side of objects. In the picture below, the Sun is in the west, which is the right of the ball here. The ball's shadow is therefore created on the east side.

 

 

In this activity, we will be looking at data collected about both outdoor shadows and indoor shadow experiments.
 

Let’s try one together.

 

Joanie and Fred conducted an experiment.

 

They drew around their shadows at three different times of day.

Using the table below, at what time were the shadows longest?

 

Time of day	9 am	12 pm	4 pm
Joanie	104 cm	54 cm	108 cm
Fred	108 cm	58 cm	112 cm

 

The answer to this is: 4 pm.

 

We can see that the longest shadows happened later in the day, when the Sun was furthest away.

 

 

Now, let’s put these skills to the test!