Been years since I instructed, but when I did full time, one thing I did with all my primary students in the C150/152 is distract them enough I could flip the fuel shutoff without being seen.
Didn't matter how many times we'd simulated an engine failure and practiced the flow, when the engine actually quit without my hand on the throttle, they most often froze, and completely ignored the steps to restore power. Only had one or two that found the shutoff without my prompting.
BTW, I always did this within gliding range of a private grass strip I knew of, just in case. Never an issue though, engine was always happy to run when fuel was restored.