Table 1.

Expanded, Extended, and Enhanced definitions and examples

Theoretical Mechanism	Definition	Examples
Expansion	Replacing time allocated for low active or sedentary activities with time allocated for more active activities.	Substituting seatwork with active learning tasks in general education classrooms. Providing a before or after school opportunity to be active, where one did not exist previously.
Extension	Lengthening time currently allocated for physical activity opportunities.	Providing additional physical education (PE) lessons per week, on top of what is currently provided. Lengthening or adding additional recess PE sessions per week or allocating more time for recess or PE on a given day.
Enhancement	Modifying an existing physical activity opportunity to increase the amount of physical activity youth accumulate during an allotted period of time.	Reducing student wait time during PE lessons to increase physical activity Increasing portable equipment options for students during recess. Providing choice among two or more activity opportunities