Okay - if you don't have the opportunity to get fully certified and instead will do a repeat DSD then the course should be conducted like this (assuming PADI):
- First, a briefing - preferably using the DSD flipchart, or the DSD cue cards for the instructor. Can be either or, but is mandatory. Paperwork completion and a short 9 question true or false quiz.
- Preferably watch the DSD DVD (not mandatory but useful)
- the briefing consists of: how pressure affects the air spaces in your body, how to keep them equalized, how to interact with aquatic life, basic buoyancy control, breathing and swimming technique, equipment introduction, underwater signals and basic skills.
- Dive 1 ( confined shallow water, maximum depth 6 metres) - skills include BCD inflation and deflation at the surface, regulator recovery at the surface, breathing from a regulator underwater, regulator removal, replacement and clearing underwater (blast and purge methods), regulator recovery, clearing a partially flooded mask, equalisation technique. The optional alternate air source prior to the second dive has technically been removed from the program but is still routinely taught (Note, if you do the experience only in a pool, only the BCD skill is required)
- Dive 2 (optional) - fun dive, maximum 12 metres, under close supervision of an instructor. The two dives can be combined without exiting the water.
That's a brief (incomplete) summary of the program to give you an up-front idea of how it should be conducted. There are variations on the theme; for the full program please PM me.
If you're not getting what you think you should be getting, don't do it, find a better shop with a quality instructor. I know a lot of people disapprove of the whole concept of a DSD but given that it exists, as an experience it should be safe and fun and wonderful, not scary.
Hope that helps,
C.