The idea of graduating students from one grade to another by age means a teacher may face a huge range of reading skills in their classroom. Since much of reading skill is based on practice and exposure, the highly resourced child may have twice or more the vocabulary of an under-resourced child.
Some say smart kids know the answers to all your questions; gifted kids question all your answers. Then, there are students with learning challenges. And it is not unusual for children to be 2x or have more than one "variation." If a child is very good at one or more skills tested, they may learn to overcome or hide learning challenges until they are older - when their methods might need to change.
There are a lot of overlapping characteristics between highly-sensitive, autistic, ADHD (poor impulse control & hyperactive brain), high creativity, perfectionistic, anxious, depressed, and learning challenged or otherwise neurodivergent minds.
- Diversity should not be surprising because the "norm" is an archetype, not a real thing.
- Even the mathematical normal changes with the population evaluated.
- Everyone has a different idea of what the "norm" should be.
- The "norm" for one child might be years ahead or behind another child in any area of learning.
Trying to tailor book selections to children may be less useful than providing a large variety of books and letting them choose.
However, when trying to maintain the interest of advanced readers, it is good to communicate with parents or guardians about whether they are comfortable with allowing their children to read books meant for an older age group. In that case, it is common to have parent sign a release or waiver form.