Science Project(3)~~ make a sundial to tell the time

Introduction:
At the same time the Egyptians invented the 'shadow clock', other cultures also developed a need to organize their time more efficiently. Amongst others, the Chinese, Greeks and the Romans developed another device for telling the time known as a 'sundial'. Sundials do not necessarily work better than shadow clocks, it is just a slight variation to the shadow clock. Make your own 'sundial' to tell the time in this science experiment.

Materials:
PROTRACTOR
STIFF CARD
COMPASS
THICK CARDBOARD
GLUE
SCISSORS

Procedure:

1. On a stiff piece of cardboard, draw a right angled triangle as in the diagram above. The short sides of the triangle should be about 150mm long, whereas the long side will be about 200mm, depending on the longitudinal angle used for your town. Make sure that you also add the base, below the dotted line.

2. Cut out the triangle, and make a fold along the dotted line to form the base for the triangle to stand on.

3. Make a thick base for your sundial out of corrugated cardboard or wood of about 150x300mm in size. Draw a semi-circle on the base as shown in the diagram above.

4. Glue the folded part of the triangle firmly to the base and place the sundial on a flat surface outside so that the triangle points north / south.

5. Mark the position of the shadow that falls on the base every hour. Notice that the shadow travels the same distance along the semi-circle every hour. On a sunny day you will now be able to tell the time by looking at the position of the shadow on your sundial!