Research on the achievement effects of teaching in the child's native language in comparison toteaching in English suffers from a number of inherent problems beyond those typical of other re-search on educational programs. First, there are problems concerning the ages of the children in-volved, the length of time they have been taught in their first language, and the length of time theyhave been taught in English. For example, imagine that a bilingual program teaches Spanish-dominant students primarily in Spanish in grades K-2, and then gradually transitions them to Englishby fourth grade. If this program is compared to an English immersion program, at what grade level is
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it legitimate to assess the children in English? Clearly, a test in second grade is meaningless, as thebilingual children have not been taught to read in English. At the end of third grade, the bilingualstudents have partially transitioned, but have they had enough time to become fully proficient? Forexample, Saldate, Mishra, and Medina (1985) studied Spanish-dominant students in bilingual andimmersion schools. At the end of second grade, the bilingual students, who had not yet transitionedto English, scored nonsignificantly lower than the immersion group on English reading. One yearlater, after transition, the bilingual group scored substantially higher than the immersion group inEnglish reading. Some would argue that even the end of fourth grade would be too soon to assess thechildren fairly in such a comparison, as the bilingual children need a reasonable time period in whic