Final answer:
A Progressive Interval 5 (PI5) schedule would be a good starting point to increase snack time sitting behavior, progressively increasing the intervals of reinforcement as the behavior becomes more consistent.
Step-by-step explanation:
An example of a progressive interval schedule of reinforcement to increase snack time sitting behavior is to start with PI5 (Progressive Interval 5), and then gradually increase the interval by a constant amount each time the target behavior is successfully displayed. This means that if a student remains seated at snack time without any issues, the interval before they receive reinforcement (like praise or a small treat) will initially be every 5 minutes, then perhaps 10, and continues to increase progressively. This schedule is designed to encourage the student to maintain the desired behavior over longer periods of time, encouraging self-regulation and persistence.