Use this 1-page blackline to copy onto 8.5"x11" colored cardstock. Cut lengthwise. You will get 4 library cards out of one sheet. Write the book title on the top few lines and the book level (e.g., 1.2 for AR level) in the circle. Keep the library card inside the book, with the top sticking out.
When a student checks out the book, remove the card, write student's name and date on the card and put with other cards for checked-out books. When the student brings the book back, just insert back into the book and file the book.
TIP: I like to have one color of card for varying reading levels. For example, lavender is 0.0 - 0.9 AR level. This makes it easy to group when returning books to their proper place.