This resource is explicitly designed to build towards this disciplinary core idea.
Comments about Including the Disciplinary Core Idea
The activities in the “Explore” portion of this lesson have students compare the motions of objects when either force or mass is changed (but not both). The “Explain” portion grounds students’ observations with a video clip and reading with interactive questions, designed to introduce Newton’s 2nd Law of Motion. The experiment in the “Elaborate” portion has students design experiments to test their conception of how the Law works. This lesson sequence does not directly address the idea of multiple forces acting simultaneously (the sum of forces), nor ideas about why some objects don’t accelerate and sometimes don’t even move (sum of forces is zero). To fully address this Disciplinary Core Idea, teachers will need to address these ideas with students, with an exploration of balanced vs. unbalanced forces and/or Newton’s First Law of Motion.