As someone who used them in school all the time and got free ones from time to time, alphasmarts if you can stomach the first generation storage spaces. We're talking something like a few gigs if you get a really premium model.

The screen is also something like a typewriter, only having two or three lines visible at a time.

If you do go that far though, there's really no reason to avoid a cheap laptop, which will probably be better in every single way...