As I was writing out post-it notes for my students with their current reading level, goal, deadline and each level that was in their ZPD, I thought I could make something a little more permanent. These are designed to be used as bookmarks by my students.
In the "You can check out books at this level:" section, I write down every possible book level they can get. So if a students has a ZPD of 2.6-3.6, I write down 2.6, 2.7, 2.8, 2.9........3.6. Most of my students do not have a grasp of decimals so this makes them able to select books independently.
Hope this helps your students!