Before publishing a book, we send it through a rigorous testing period with a number of literacy professionals, including Reading Recovery® and classroom teachers. These teachers work together to assign levels to the books. These are levels that we refer to on our website and in our catalog as "intervention levels."
Unfortunately, it does take the Reading Recovery® Council of North America (RRCNA) between two and four years to assign levels to books, so it is vital that we determine working levels in the meantime. When a book is assigned a level by RRCNA, we ask our pilot teachers to immediately assess the intervention levels that we had previously assigned.
Sometimes, we determine that we do not agree with the RRCNA levels. It is because of this discrepancy that we continue to reflect our intervention levels along with the designation that a title appears on the RRCNA booklist. All teachers use slightly different criteria in making a subjective ruling as to the level of a book. Many teachers choose to use our intervention levels rather than the RRCNA levels, and many teachers choose to go the other way. Still more teachers assess those books for themselves and choose to use them at yet another level.