Windmills are used to turn wind energy into power we can use for different purposes. When the blades or sails on the outside of the windmill catch the wind, they spin converting that spinning into productive energy. Windmills were originally used to grind grain and pump water. Today, we have modified the windmill into turbines to make electricity. If you want to build your own windmill for a science project, you can easily do so with supplies you have in your house.
Clean the inside of a half gallon paper milk carton using soap and water. Turn the cleaned carton upside down and allow the water to drain out. Leave it to dry completely overnight.
Place 1 to 3 inches of sand into the bottom of your clean and dry milk carton.
Use a pencil to poke a hole into the side of the carton about half way up. Press the pencil straight through to the other side of the carton so that you have two parallel holes on opposite sides of the carton.
Insert the end of a straight plastic drinking straw into a cork. If you are not able to press the straw through the cork easily because the cork is too dense, insert the tip of your pencil into the cork and press it in to make a carved out circle. Then remove the pencil and insert the straw into the hole you left behind.
Insert your straw through the holes you made in the carton in step 3. The cork should be on the outside on one end of the straw. Attach a pinwheel to the other end of the straw using a straight pin or a bit of super glue; however, avoid heavy glues, such as craft glue.
Tie the end of a 3-foot length of thread to the cork. Tie the other end of the thread to a paper clip.
Blow on the pinwheel of your completed windmill to make the paper clip go up and down.
Cut a four inch square out of a piece of construction paper.
Cut on a diagonal at each corner, in towards the centre. Do not cut all the way through. Stop about an inch from the centre.
Bend every other corner in towards the centre. Do not fold or crease the paper. This will create the basic pinwheel shape.
Insert a stick pin through the centre of the paper and the four corners you just bent in step 3 to finish.
If you prefer, you can purchase a pinwheel instead of making your own.