TBE has supported English learners (ELs) with their first language in the transition to an English-only classroom, and the idea that maintaining, supporting, and further refining the ELs' first language will connect in learning English. This idea is further clarified by Stephen Krashen (1996): When schools offer children a quality education in their primary language, they offer them two things: knowledge and literacy. The knowledge that children gain through their first language helps make the English they hear and read more understandable. Literacy develops in transfers from the primary language to the second language. The reason is simple: because we learn by reading, that is, by making sense of what is written on the page, it is easier to learn to read in a language we understand. Once we can read in one language, we can read in general. This was the main driving force behind TBE. If implemented correctly, students would walk away just as proficient in their first language as in English, but with this idea some have criticized whether there were sufficient resources to achieve that outcome and whether or not it was able to undertake it in a timely manner to actually teach students