# Overview of Section Resources

Section 1: Forces and Motion
Students begin by deﬁning motion in relation to a reference point. They infer the relationships among force, speed, and mass. Speciﬁcally, they use the effect of gravity to show how force can cause motion and how it relates to mass.
Section 2: Measuring Force
Students expand their knowledge of force and motion by learning the difference between weight and mass and using a spring scale to measure weight. They estimate the weight of objects and then ﬁnd actual weight. They demonstrate how forces act in pairs that are equal in size but opposite in direction.
Section 3: Friction
Students investigate the force of friction. They observe that lubricants and rolling objects decrease the amount of friction between surfaces and use bar graphs to display their data. They also investigate the effect of friction on falling objects and determine that air resistance depends on the shape of an object.
Section 4: Inclined Planes
Students begin their exploration of simple machines by investigating inclined planes. They demonstrate that some machines make work easier by reducing the force needed to do a job. They also see how two other simple machines—the wedge and the screw—are modiﬁed inclined planes.
Section 5: Levers
Students continue observing simple machines by investigating levers. Their investigations show that levers, like inclined planes, make work easier by allowing the user to apply less force through a greater distance.
Section 6: Wheels and Axles and Gears
Student investigations of another simple machine—the wheel and axle—show how work can be made easier by changing the size or direction of a force. They also show that gears multiply force when a larger wheel turns a smaller wheel that is connected to it.
Section 7: Pulleys
Students show how pulleys make work easier by changing either the size or the direction of a force, or both. They observe that the force used on a pulley system becomes less as more pulleys are added.
Section 8: Sound
Students observe that force can result in vibration of particles, causing sound. Students investigate pitch and volume of sound and predict the results of investigations involving sound. Students then apply principles of sound to musical instruments.
Section 9: Magnets
Students conclude their investigation of force and motion when they show that the force of magnetism can cause motion.