Clarification Statement - S.3.PS.2.1.CS:
Examples could include an unbalanced force on one side of an object can make it start moving; andbalanced forces (including friction) acting on a stationary object from both sides will not produce any motion at all.]

Assessment Boundary - S.3.PS.2.1.AB:
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

Science and Engineering Practices - 3-5.SEP3.2:
Plan and conduct an investigation collaboratively to produce data to serve as the basis for evidence, using fair tests in which variables are controlled and the number of trials considered.

Disciplinary Core Ideas - S.3.PS.2.1.DCI:
PS2.A: Forces and Motion •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.) PS2.B: Types of Interactions •Objects in contact exert forces on each other.

Crosscutting Concepts - CC2.3:
Cause and effect relationships are routinely identified.