I was invited to give a guest lecture on "sound" at my daughter's (12 years old) school the other day. I created a small presentation to back up the main elements of the talk: an analogue synthesizer connected to an oscilloscope.
The interesting bit: 12 years old + Hebrew, a language I only master passively (I understand, I can speak a few words, I totally cannot write anything). So my daughter did some translating, and for the slides I relied heavily on icons.
Yes, icons. I made fun of icon slides many times in this blog, but I must say, when used the correct way they can make great slides. I think the key to icons is to pick really original and good ones, use them in very big sizes, use flat designs without colors/shadings/gradients, use icons in a consistent style, and use the same ones repeatedly as a memory shortcut to the same concept.
To find icons, I used the noun project, a much better source for icons than stock image sites.