I don't recall being assigned books to read until about 8th grade or so. But I grew up reading everything under the sun.
I read a lot of simple books i.e. choose your own adventure series. For those of you who don't remember them, it was a series that at the end of a section you'd have a choice to make. Do this turn to page XY or do that and turn to page ZA. Every section had a choice, not great reading but it was fun. I do remember in 4th and 5th grade we had a common recess period 4,5,6th graders and one of the teachers had a bookcase of simplified myths of differing peoples and lands. I read all the Roman, Greek, Norse, some Native American, Japanese, type myth stories. I think that was my first, albeit super simple reading of "the Odyssey." I recall reading about Jason and the Argonauts as well.

Going back to elementary I just don't recall reading much specifically. I recall reading "Pickle books," all the Richard Scary books, step-up books. I can't remember when I read Mouse and the Motorcycle I'm thinking 2nd or 3rd grade.

Anyways my point is that books can't be forced. If your wife wants to encourage reading I'd reccomend having her set aside a time period which she reads to the class. After a month or two, start periods of time which the children can get a book to read themselves Dr. Seuss, Richard Scary etc... Have the students do a simple book report, then choose based on said report, a book to read for a story time.

I can't recall whether it was 2nd or 3rd grade, but we had a reading contest. A book was read and a simplified prepared book report was submitted, author, characters, subject. All I really remember was my group won by a devastating margin. We read more books than all the rest of the groups combined.

Another fun activity based in reading was in third grade we had a 4-6 child group. In the group we made up our own story, illustrated it. Then when it was complete the teacher laminated the book, published, and then it was put on display in the elementary library.