Wrap this rectangle around your pencil, taping it to make a cylinder. Next, cut out the fins from the template and tape them at 90-degree angles to the rocket fuselage near the eraser of your pencil.

Whether in the real world, depicted in cartoons, or in a hobbyist's back yard, rockets always seem to have fins. Or if not fins, at least some other kind of protrusions along the outside -- they ...