An anemometer is a gauge used to measure the direction and speed of wind, usually in miles per hour. While it is not possible to make a professional anemometer at home, it is possible to construct a device to give you an indication of wind speed. Making your own anemometer requires few resources and is a great classroom activity or educational home craft project.
Cut away the lip of each cup with your scissors to make them lighter, ensuring they all remain equal sizes.
Colour one of your cups with your favourite colour. Be sure to choose a colour that will stand out -- this will help you count the revolutions when the cups are spinning.
Lay the two strips of cardboard on a flat surface. Position them to form a cross or "plus sign." Use your ruler to make sure each length of the cross is equal before stapling them together. Use at least two staples at the point they cross to fasten them together securely.
Draw two diagonal lines on the intersection of the cross (where your staples are). The point at which they cross is the midpoint and will be needed later.
Staple each cup to one end of the cross. Make sure they are all positioned as wide as possible and all face the same direction (clockwise or counterclockwise).
Lift your cross with the cups on the underside. Push the pin through the midpoint you determined in step 4 (where the two diagonal lines meet) and fasten the pin to the centre of the eraser on the back of your pencil.
Mold your modelling clay into a mound with a flat, solid base. Stick the sharpened end of your pencil into the clay mound so it stands rigid when you let go.
Blow on your cups to check that the anemometer rotates freely. If the movement is restricted, loosen the pin by lifting it slightly higher from the pencil eraser.
Measure the wind speed. Position your anemometer so that it faces the wind. Using your stopwatch, count the number of revolutions the marked cup makes in 30 seconds, then double this amount to calculate the wind speed in revolutions per minute.