These are clearly slides, meant to be fullscreen on a projector. Up/Down, Left/Right, PgUp/PgDown all work, much like they would in powerpoint. I'm a little baffled by this threads hostility towards the lack of a friendlier design.
I'm on my iPhone and its totally unviewable. It looks like I can see maybe 20% of a slide, with parts if that covered up by black bars. I can't resize or re-zoom.