All of the choices below are examples of times when using a shadow is not a practical way to compute indirect measurements. Select the one you think is the most likely use.

When it is impractical to create similar triangles using shadows, you can create similar triangles using a mirror. The following steps will show you how this is done. You can read or print these steps then try them on a few objects that you already know the height.

The materials that you will need to complete this activity are; yard stick and/or tape measure, mirror, writing materials and a calculator.

You will use your eyes to look in the mirror. So you will need to know your height from eyeball to floor. Get a tape measure and measure from the floor to the corner of your eye. We will call that your "eye-height" so record that measurement for use later on. (mine is 67 as shown in the example on the right)

Now let's measure a wall in your house. Most walls are 8 ft tall, but yours may be different. Place the mirror exactly 5 feet from the wall.

Now move backwards until you see the top of the wall in the mirror. (Make sure that you can just see the top of the wall no ceiling!)

Mark that point and measure and record the distance from your heels to the mirror. (Mine was just under 42 inches - I will remember to round my answer up later on)

Now compute the height of the wall! Was your wall 8 feet tall?

Now check the closeness of your answer by measuring the wall with the yard stick or tape measure. I hope you did well. Follow these steps to measure many different things. You might try your TV set, your basketball hoop, a tree in your yard or what ever you can imagine. Make sure to click OK below to get extra credit for trying this skill!