How to make a Periscope

You need:

• a piece of strong cardboard, 32cm x 50cm
• scissors
• sticky tape
• 2 handbag mirrors, 6cm x 10cm
• a ruler
• pencil
• 2 square pieces of cardboard, each 6cm x 6cm

What to do:

     1.Using the ruler, divide the cardboard into four equal parts, each 8cm wide. Draw around a 6cm square twice, as you see in the picture. Cut these squares out.

     2. Cut the 6cm square in half diagonally to make 2 right angled triangles.

     3. Place the triangle on the top strip of the paper, as shown in the picture.Draw a line along the  diagonal of the triangle and cut through it to make a notch. Do this again in the 3 other places shown in the picture. Fold the cardboard into shape. Join the sides with sticky tape.

      4. Slide the 2 mirrors through the notches.

      5. Get behind an obstacle (such as a wall, or a window sill) so that the periscope is sticking above your head.Look through the square at the bottom. Enjoy!!

What happens?

In the mirror inside the periscope you will see a reflected image of whatever is behind the obstacle.

Reason :

This is because the light which rebounds from the objects or people on the other side of the obstacle strikes the mirror at the top of the periscope. Because of the angle of this mirror, it is reflected in the bottom mirror. You can use your periscope to look at something without being seen - just like submarine crew who need to survey the sea  before coming up to the surface!