2. How do students in TWI programs compare academically to students in other types of educational programs?

Several investigators have examined the reading and math achievement of students in dual language programs at late elementary or secondary levels to determine the long-term impact of TWI programs (e.g., Cazabon, Nicoladis, & Lambert, 1998; Collier & Thomas, 2004; Howard, Sugarman & Christian, 2003; Kirk-Senesac, 2002; Lindholm-Leary, 2001, 2005).

These studies showed that overall both English language learners and native English speakers made significant progress in both languages; both groups scored at or well above grade level in both languages by middle school; and both groups performed at comparable or superior levels compared to same-language peers in other educational settings. On norm-referenced standardized tests of reading and math achievement in English, native English speakers outscored their English-only peers in English-only classrooms. English language learners who had learned English in a TWI program scored significantly higher than their English language learning peers who had studies in other kinds of programs in the state and also performed on a par with native English speaking students in English-only classrooms (Lindholm-Leary, 2005; Lindholm-Leary & Borsato, in press).