high-low book
n.— «Then there are the so-called teen high-low books for those with a lower vocabulary level. “They are carefully plotted, they’ve got good characters but they are written at a vocabulary level that is better designed for the reluctant reader.”» —“Kids’ book market blooms” by Camille Bains in Vancouver London Free Press (Ontario, Canada) May 15, 2006. (source: Double-Tongued Dictionary)