We had a basic student who was certified provisional at the age of 12.
He was doing the Basic Open water course at my university.
He made a few mistakes.
While doing a buoyancy check in the pool, he exhaled fully and sank to the bottom.
Next he inhaled and rose to the top, not exhaling.
He remembered that he shouldn't hold his breath, but he just wanted to see if he could do it. I think air embolism skipped his mind.
As a note, I was the TA and made a lack of judgement to stop him. I wasn't sure if he had inhaled or not.
He was completely fine though.
The instructor and other TA's were working one on one with the other students. We had a class of 7.
The next error he made was to breath a tank to 0psi on the surface, after we were packing our gear up, because he wanted to see how it felt. This was also during a pool session as well.
Needless to say he wasn't allowed to attend the checkout dives. Instructors orders.
He now has to retake the safety lectures and attend a few more sessions to convince the instructors of his ability.