“…Not surprisingly, proficiency rates for ELLs on state assessments increase as their language proficiency increases (Cook, Boals, & Lundberg, 2011). Several researchers have found that it takes ELLs at least five years to acquire proficiency in academic English and that the rate of acquisition is influenced by the level of proficiency at which students begin, with students at higher levels of proficiency acquiring English more quickly than students who begin at lower levels of proficiency (Cook et al, 2011;Genesee, Lindholm-Leary, Saunders, & Christian, 2006;Hakuta, Butler, & Witt, 2000). To address these concerns about validity, researchers have recommended that educators use multiple sources of data to assess the academic progress of ELLs, to make decisions based on assessments that are valid and reliable for ELLs, and to take into account, as much as possible, assessments of skills in the home language (Echevarria & Hasbrouck, 2009).…”