Professor jackson periodically gives his students pop quizzes on the reading assignments. to encourage students to complete the reading assignments, the schedule of reinforcement he should use for the pop quizzes is a schedule.

variable ratio

Explanation:

Professor Jackson periodically gives his students pop quizzes on the reading assignments. To encourage students to complete the reading assignments, the schedule of reinforcement he should use for the pop quizzes is a variable ratio schedule.

Professor Jackson  used strategy called  variable ratio to motivates students in reading assignment by using pop quizzes.