Final answer:
Barbara's decision to hire an additional teacher when student enrollment exceeds 35 is an operational decision.
Step-by-step explanation:
The decision by Barbara to hire an additional teacher whenever the student enrollment in a grade goes beyond 35 can be classified as an operational decision.
Operational decisions are related to the day-to-day operations of an organization, involving routine activities and immediate actions to achieve specific goals.
In this case, the decision to hire an additional teacher is based on a specific condition - when student enrollment exceeds 35 - and is aimed at addressing the immediate need for staffing in response to this condition.