According to RAND, "Despite long-term and ongoing efforts to close the achievement gap between disadvantaged and advantaged students, low-income students continue to perform at considerably lower levels than their higher-income peers in reading and mathematics. Research has shown that students' skills and knowledge often deteriorate during the summer months, with low-income students facing the largest losses. Instruction during the summer has the potential to stop these losses and propel students toward higher achievement." You can purchase this publication in book format or download it as a free e-book.