PS2.A: Each force acts on one particular object and has both strength and a direction. An object at rest typically has multiple forces acting on it, but they add to give zero net force on the object. Forces that do not sum to zero can cause changes in the object’s speed or direction of motion. (Boundary: Qualitative and conceptual, but not quantitative addition of forces are used at this level.)
Cause & Effect
3-PS2-1: Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object. [Clarification Statement: Examples could include an unbalanced force on one side of a ball can make it start moving; and, balanced forces pushing on a box from both sides will not produce any motion at all.] [Assessment Boundary: Assessment is limited to one variable at a time: number, size, or direction of forces. Assessment does not include quantitative force size, only qualitative and relative. Assessment is limited to gravity being addressed as a force that pulls objects down.]
By the end of this lesson, the student should able to:
Observe the effects of a force
State the effect of a force
Duration: 30 min
Resources / Materials
Welcome students to class.
Get students into groups of 3-4.
Distribute each group with 3 balls (labeled A, B and C).
Inform students that they are going to complete some challenges.
Move Ball A which is stationary
Make Ball A move faster and stop moving.
Change the direction of Ball A
Place ball A on the floor and tell students that they can make use of the other balls to complete the challenges. Get students to think in their groups how they would be able to complete the challenges.
Get students to share how they have accomplished the different challenges.