Gravity & Magnetism
Grades 2-3 | 20 sessions
Students learn about forces, including gravity, magnetism, and electrostatic force. They also learn to set goals, use text features as they read, and write scientific explanations. They learn and use scientific vocabulary, such as attract, repel, evidence, and investigate.» Download Unit Description
Students engage in hands-on activities, such as inventing and sharing "magnet tricks" to explore magnetic poles. They also build an "anti-gravity" www.ce to investigate gravity.
Students are provided with many opportunities for small group discussions to help them make sense of science ideas. For example, students discuss which materials are attracted to magnets and debrief their "magnet tricks" using the terms attract and repel.
Students read four science books, including Mystery Forces, which challenges them to figure out which forces are at work in a variety of scenarios. Students use comprehension strategies such as setting goals for reading, and learn how to navigate informational text.
Students write scientific explanations, including an explanation about what magnets attract. Throughout the unit, students write to record observations and reflect on their learning.
Nature and Practices of Science
The Gravity and Magnetism unit introduces students to the idea of a force, with a focus on forces that can act at a distance, especially gravity and magnetic force. These are important foundational concepts in physical science that students will build on in coming years.
Forces: A force is a push or a pull between objects. Students learn that forces can cause changes in the motion of an object- for example, by making it start moving, making it move faster, or stopping an object that was moving. Students learn everyday examples of forces, for example someone kicking a ball, pulling a wagon, or pushing someone on a swing. Students learn that some forces- gravity, magnetic force, and electrostatic force- can act at a distance, when the two objects involved are not touching each other.
Magnetic force: Students learn that magnetic force can be a pull or a push. Students discover that magnets attract some, but not all, things that are made of metal. Then they discover that those metal objects that magnets attract all have iron in them. They learn that while magnets only attract (pull) iron objects, they can pull or push (repel) other magnets. Every magnet has a north pole and a south pole. Opposite poles attract each other, while like poles repel each other. Students learn that the Earth acts as a giant magnet. Students learn that magnetic force can act at a distance and can act through materials. The farther away the magnet and the other object are from each other, the weaker the magnetic force is.
Gravity: Gravity is a pull (never a push) between all objects. Gravity is only strong enough for us to observe it when at least one of the objects- such as the Earth- is VERY large. All objects on Earth experience a pull of gravity down toward the center of Earth. Students learn that weight is a measurement of the force of gravity on an object. Students learn that other planets (and the Moon and the Sun) also pull objects with the force of gravity, and that the force of gravity is different on different planets. They discover that therefore the weight of an object (or a person) would be different on other planets. Like magnetic force, gravity is weaker the farther the two objects involved are from each other.
Electrostatic force: Electrostatic force is a push or a pull between a charged object and another object. Objects can become charged when they are rubbed. Common examples include clothing that becomes "sticky" after spinning in the dryer, or a balloon that attracts hair or sticks to a wall after being rubbed. Like gravity and magnetic force, electrostatic force is weaker the farther the two objects involved are from each other.