Natural context is any place or circumstance which is typical for an activity or event.
The car or the school bus is a natural context for this event. Frequent practice is the opportunity to do something often enough that a skill is learned or perfected. Lifting the clamp on a seatbelt to release it is a skill. Lifting the clamp on the student's own seatbelt as well as those of several of his peers when the school bus stops is frequent practice .