Regarding the 1918 pandemic, the factor that troubles infectious disease and public health researchers is who died - not only the elderly, infirm and very young as is typical with influenza, but significant numbers of seemingly normal healthy adults. There are lots of hypotheses and plenty of conjecture as to why, but the best guesses reason that the 1918 strain was genetically novel and thus may people exposed had no (partial) immunity whatsoever derived from previous influenza exposure. This newly emerged virus was also thought to be better able to "take up residence" deeper in the lungs resulting in much more severe infections with complications like pneumonia and accompanying greater mortality.

This is the situation the DoD is expecting in a pandemic.

"The City of Gold and Lead" by John Christopher. I recall I lucked onto it in the 3rd grade. My gateway book to Science Fiction/Alternate Universe/Fantasy.

The Magic Tree House series kept my kids attention-Mary Pope Osborne

A lot of Jules Verne's work has been edited for younger readers.

As other have stated, let your kids guide you to what interests them. Let's hope they have access to a good reading program in school.

I've found any of the Newbery Award winners from the ALSC are usually good reading. Those librarians are on to something.