Use a pendulum to draw patterns that are made of sand.
Observe the paths to demonstrate symmetry and pullback distrance.
Sand patterns help the students see the center point of designs and the symmetrical paths of the pendulum. Once students see the center point, they will discover that the distance from the center point to both edges of their design is the same. This measurement will be referred to as pullback distance. In one cycle or round trip, the pendulum travels equal distances from the center. As the pendulum continues to swing, it will lose motion, causing a loss of amplitude (the size or extent of the pendulum’s swing) and fewer round trips.
Pendulum comes from the Latin word pendulus, meaning “hanging.” A pendulum is an object hanging from a fixed point that, when pulled back and released, swings due to the forces of gravity and inertia. Gravity is the pull of the earth that draws all objects in or near the earth toward its center. Inertia is the tendency of a moving body to stay in motion, or the tendency for a body at rest to stay at rest.
Source: http://britton.disted.camosun.bc.ca/pendulum/teacher.html
