This post-reading assignment was more meaningful to students than a multiple-choice test or an essay about character or theme. That's because it provides 10 options for letters students can write to real or fictional characters.
Included is a suggested outline that works for most of the letter options. Depending on your class discussion, you might want to adjust a couple of the options, but it's a pretty solid list. Use it as multiple homework options or as an in-class writing. Send them using your school mail if you really want to show students they can make a difference with using writing.