“…Past research, which has mainly been performed in the United States, focused on the question whether bilingual approaches to second language teaching and learning are superior to monolingual approaches. These studies have yielded mixed results, however, and the quality of most evaluations is questionable (for reviews see Francis, Leseaux, & August, 2006;Greene, 1997;Limbird & Stanat, 2006;Rossell & Baker, 1996;Slavin & Cheung, 2005;Söhn, 2005;Willig, 1985).…”