A friend of mine, a librarian and lifelong reading enthusiast, shared with me the Excel spreadsheet her newly minted high school graduate niece keeps as a personal book record. Organized from about kindergarten through the present, this spreadsheet is an effective and evocative album closely akin to a well organized collection of snapshots and class pictures of this 18-year-old's reading experiences--or places she's gone and documented and remembered across her book life to date. My friend noted that both she and her niece were aware that the list tends toward books that "aren't on the reading level" of someone who expects to enter university in a few months. That expressed concern, even as a casual observation, suggests an assessment of one's reading life that flies in the face of why we readers read.
A couple of recent studies  and blogging accounts of them direct--I would say misdirect--attention to the aspect of reading that is simply mechanical rather than aesthetic, social or formative. Like the cancer of the Accelerated Reader  program that equates reading books with passing quizzes on factual information remembered from them, how we talk about books and reading choices with youth is endangered by a bloodless, intolerant perception of book reading as something that corresponds to grade level accomplishment, grade making ability and a rigid ladder up which one must ascend rung by rung, without a look backward let alone a step off the ladder and into the twisting boughs of the tree.
Book reading--in which "book" is a sustained narrative with complex underpinnings of meaning and message, connotation and denotation built of language, point of view, evocative cultural elements and more--is not endangered by changing platforms. But we are endangering future potential book readers when we consistently draw attention to their mechanical abilities, intellectual memory and expressions rather than allowing them to bathe their minds and hearts in whatever the books open for them.
Some years ago, the math department at a local high school required each student enrolled in any level of math, to read four works of fiction during each semester. The fiction requirement was loosely constructed and those at lower levels of math achievement did not need to concern themselves with the added attribute more sophisticated maths students were to use in making their reading selections. For the calculus, statistics and other higher level classes, fiction books were to be read with an eye for the math in the fiction they selected. No, not the math books they selected, but the fiction. The assignment must not have been a lone wolf among contemporary high school math departments because I was ecstatic to discover a most helpful guide published by the California Department of Education, a list  regularly updated with input from language arts teachers, public and school librarians and, of course, math and science teachers. (Yes, there are nonfiction works on this list, including plays and poetry, but not textbooks).
I've heard John Green , the young adult literary novelist whose second book  won both literary honors and a place on CDE's math literature list, discuss how reading--and for a writer, the reading done of his books by others--strikes him as a collaboration, a collaboration between the author and each reader. That collaboration isn't, of course, singular, he is quick to point out, but is a different one with each reader because each reader brings to the author's book his or her own unique understanding, appreciation, and concerns or interests.
That's reading on the level: collaborating with the book (and the author) as a reader, climbing off the ladder and into the tree where you, the reader, can get what is the best view for you.