For you, since you're uncertified I would follow what your instructor tells you about logging dives. After that you can follow your agencies policy so you won't have any problems signing up for classes in the future.
If you decide to just dive and take a break from classes (highly recommended), then log what ever dives you feel like logging. Your dive log is a your journal and you'll feel a lot better when you can read and look back on your dives. Just keep in mind that some instructors may not count pool dives or very short and shallow dives.
Between the scientific and recreational dive programs at my university, in general a dive is:
- Any time you breath compressed air at depth (sci)
- Pool dives aren't officially logged, just logged for practice on separate sheets of paper (sci)
- Anytime you breath compressed air at a minimum of 10ft for 10mins (rec)
- pool dives are never logged (rec)
- Any dive(s) separated by at least 10mins will count as 2 dives; exceptions to this are during class hours
ie. rescue or basic classes where students spend 3mins down and 13 mins up discussing etc.
For me personally:
I log any dive that has a purpose, whether that's for fun, for a class, or for science. I do NOT log pool dives since that's not an open water dive.
Any dives that are separated by at least 10mins count as 2 dives for me. The only exception to this is if I haven't left the water, which usually occurs when I'm TA-ing for a class.
A few examples:
- I'll spend 3 mins deploying a sand anchor then spend about 2 hours total on the surface. In those 2 hours I'm descending and ascending, collecting 2-5min dives. By the end of that day I'll just total up all my dive times since all those "dives" had one purpose, therefore it's one dive in my log book.
- I once did a 15ft dive for 9mins to collect bags of sand. I logged it as one dive
- I did a 38min dive with my buddy and surfaced a few feet from shore. We spent a little over 10mins waiting for the waves and surf to subside. Then we descended, waited a bit longer, and did an exit crawl out. I logged that as one dive.