Use a ruler to draw a square on a sheet of heavy paper, preferably cardstock. Typically patterns call for a square between 6 and 8 inches wide. The larger the square the larger the turbine will be, and the easier it will be to fold.
Decorate the square as desired. You can use paints, crayons, markers, stickers, glue-on objects, etc. Make sure any glue used a dried completely before going on to the next step.
Divide the square into four equal quarters by drawing two diagonal lines across the square. Use a ruler to draw these lines from corner to corner.
Make a cut at one of the corners. The cut should be half the distance from the corner to the center of the square along the line drawn.
Repeat this process, creating a cut at each of the four corners. Each corner now has a right and left half, divided by the cuts you have made.
Use a hole punch, or the end of a pencil, to poke a small hole in the left half of each corner.
Use the hole punch or pencil to poke a hole in the exact center of the square.
Bend each of the corners with a hole to the center of the square, lining their holes up with the hole in the middle of the square. It is important that you do not fold or crease the paper as you bend the corners over. This will flatten a section of the turbine, and limit its ability to catch wind.
Push a brad through the 5 paper layers, and use it to affix the layers to one another.
Push the end of the brad through a plastic straw. You may have to make a small hole in the straw with scissors to get it started.
Bend the ends of the brad to affix the straw to the pinwheel. It must be loosely connected for the turbine to turn correctly.