MS-PS2-3 Ask questions about data to determine the factors that affect the strength of electric and magnetic forces.
Clarification Statement: Examples of devices that use electric and magnetic forces could include electromagnets, electric motors, or generators. Examples of data could include the effect of the number of turns of wire on the strength of an electromagnet, or the effect of increasing the number or strength of magnets on the speed of an electric motor.
Assessment Boundary: Assessment about questions that require quantitative answers is limited to proportional reasoning and algebraic thinking.
This resource is explicitly designed to build towards this performance expectation.
Comments about Including the Performance Expectation
Students compare data (number of metal staples picked up with two versions of electromagnets) in order to determine which electromagnet exerts the strongest force. They then devise and run their own experiment, changing one variable about the electromagnet to see what effect it has on the strength. The lesson uses the words “power” and “intensity” instead of the word “force” - a teacher will need to change that, and to ensure that students enter the lesson knowing what a force is.
To fully address the idea about the strength of both electric and magnetic forces, students will need to understand the link between the two, and how the strength of one implies the strength of the other. The post-activity assessment suggests students possibly be allowed to increase the number of batteries; by encouraging this experiment, students could see more clearly the relationship between strength of electric force and strength of resulting magnetic force.