So more or less, write what you want to SAY in the notes bit, and then really enhance that rather than vomit it all up onto the screen. Words should be things that really need to pop, or are hard to spell, etc. How much better does it place people in history to see pictures of them, and life at this time? Think of Ken Burns' documentaries - still pictures which seem to come to life when there's music and speech over them. Suppose, while teaching a segment on nineteenth-c American poets, you include pictures of the Civil War (when appropriate), or cozy, Longfellow-y etchings. Or the illustrations of Abolitionist tracts, or stills for Gone With The Wind? Or haunting fiddle music playing? Or Sacred Harp music, the rawest thing to come out of the 19th century except for Crimea and Jack the Ripper.
Warning: Sacred Harp music. Turn down the sound a bit. Srsly.