Opportunity to make more user friendly.  When you have a training session in the calendar, and you going into the attendance list to mark that people have attended.  If you try to select people or check all on a page of people, and then go to the next page (ie. multiple pages of attendants) to try and pick more people, the original people selected become unselected when you go back.  Thus, if you want to select multiple people that are on different pages, you have to do it piece-meal a few at a time, or one page at a time basically.  This adds alot more time to get this done, You should be able to have the selected people stay selected as you go from page to page.