Who is the educational activist known for significant contributions to second language acquisition and bilingual education?

Steven Krashen is recognized as an educational activist who made significant contributions to second language acquisition and bilingual education. His theories, particularly the Input Hypothesis, emphasize the importance of comprehensible input in language learning. Krashen argues that for effective second language acquisition, learners need exposure to language that is slightly above their current proficiency level, which supports natural learning processes similar to those used by children when acquiring their first language.

His work has influenced not only educators but also policies regarding bilingual education, advocating for immersive environments that support language learners in meaningful contexts. This advocacy for understanding language acquisition processes has made a lasting impact on teaching methodologies and policies in educational systems that cater to multilingual students.

The other individuals mentioned have contributed greatly to educational theory, but their primary focuses do not center on the specific areas of second language acquisition and bilingual education that are central to Krashen's work.