NSES Content Standard B 
Physical Science: Motions and forces
Grades 5-8, page 154

If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude. Unbalanced forces will cause changes in the speed or direction of an object's motion.

Benchmark 4F The Physical Setting: Motion
Grades 6-8, page 90
An unbalanced force acting on an object changes its speed or path of motion, or both. If the force acts toward a single center, the object's path may curve into an orbit around the center.