First graders have learned all about the screws and their everyday use in holding objects together.  We have also found many examples in our classroom including those in our furniture, water bottles, computers, wall outlets, and light fixtures.  Wrapping a right triangle around a pencil, helped us to see that  a screw is an inclined plane wrapped around a central cylinder.   Students especially enjoyed making their very own toy screw, a twirling helicopter.  Our toy helicopters act as a simple machine by spiraling as they drop.  The blades act as a screw by helping to lower (or lift) using less force.  As the helicopter twirls, it drops with less force and lands softly on the ground.