A little known fact... the Mac supports the use of the space bar for scrolling pages. If you are using a full keyboard, this is no big deal. But for laptops and other keyboards without page down and page down keys, I find it awkward to remember to hit the function key and then the down and up arrows. If you find that awkward too, trying using the space bar instead. You can use the space bar to page down. Hitting Shift and the space bar will page up.