There will be losts of things that the instructor does that you don't see the point of immediately. Best option is to ask at the time, while it's relevant and the instructor can put it into context. Your aim should be to understand the instructors reasoning behind a decision to do something.
Try the Misc section of
www.afors.com
or
www.thehanger.co.uk
(The TheHanger link may not work - I always have trouble with this site, but it is very good if you can get to it!)