Making a small wind turbine out of straws can model larger-scale versions that generate electricity. This turbine project includes miniature airfoil blades and pivots on a central axis. It also can illustrate how "wind energy" is turned into "rotational energy" using "turbines."
Select the straws to use for your turbine. Large straws catch more wind but tend to bend more. Bendy straws are inappropriate for this project because of the "bendy" portion.
Cut two, 4-inch pieces of straw tubing. Cut down the sides of the tubes to separate the tubes into four half-tubes. Stack the half tubes to make sure they all are the same size. If not, cut them so they all are the same length and width.
Cut the stack so that the straws slope inward on one side and are all uniform. The cut should start at one end (about 1/3 of the way in from the side) and continue down to the far corner of the straws. Keep the large part of each half-tube in the stack that you cut, which is now a "blade."
Fan the blades out so they overlap at their wide base. Glue the blades in this position with craft glue. Wait for the glue to dry.
Build the base/tower. Take a fresh straw and, using scissors, split the end into four pieces that you will bend outward like flower pedals. Glue these petals onto the cardboard so that the shaft of the straw sticks upward.
Pull the eraser out of the end of a pencil. Slip the eraser into the tip of the straw. Pin the center of the blade wheel to the eraser with a thumb tack, going through the end of the straw into the eraser.
Blow gently into the blades of the windmill to make it turn.
The blade wheel should be separated from the straw with a small, flat piece of card stock between the straw and the blade wheel that is the size of a quarter so the blades don't brush the against the tower, which will interfere with rotation. If the glue interferes with the turning of the blades, scrape the part of it off that interferes.
Beware of sharp objects like scissors, thumb tacks, and the edge of paper or plastic. Children should be supervised when making this project and safety scissors should be employed.