Here are some quotes from Focus on Content-Based Language Teaching (Lightbown, 2014).
Is CBLT More Effective than Traditional Language Instruction? Why?
“CBLT can be efficient (…) In foreign language settings, this ‘two for one’ approach can increase the amount of time students spend in contact with the new language without taking time away from their regular curriculum. In second language settings, students can continue to make progress in their academic subjects while they are still learning the new language.”
“CBLT can be motivating. Because the academic content must be learned, students are more motivated to learn the new language than they might be in classroom activities designed to teach the language only.”
“CBLT can promote advanced proficiency. Learning subject matter content entails the use of academic styles of grammar and discourse as well as increasingly varied and sophisticated vocabulary. This prepares students for further academic, personal, or work-related language use outside the classroom.”
One of the questions that is often asked about instruction that focuses on language is whether it should be provided in separate lessons or integrated into content-based lessons (Spada & Lightbown, 2008).
“Both kinds of instruction are important for CBLT students, with the added observation that when language-focused instruction is separated from content classes, it should include focus on language features —vocabulary, grammar, style— that students will need while doing their academic work. Furthermore, during content-based lessons, the language features that were in focus in the language-focused instruction should be highlighted, and feedback on students’ use of these features should be offered.”
In CBLT, if students understand the academic content, language learning will take care of itself.
“As Lyster (2011) remarks, ‘contrary to the “two for one” nomenclature, nothing comes for free…. a great deal of attention still needs to be drawn to the second language, which needs to be manipulated and enhanced during content teaching’ (Lyster 2011, p. 612). One useful framework for thinking about what students need as they learn language and content is Nation’s Four Strands, with three out of four strands devoted to activities that are meaning-focused and a crucial fourth strand in which the challenges of learning the language itself can be in focus.”
It is not appropriate for teachers to correct students’ language errors during content-based lessons.
“In providing feedback on language during content lessons, teachers need to make sure that students know when the feedback applies to the language rather than the content. Furthermore, the feedback should target a limited number of language features, especially features that are content-obligatory or content-compatible.”
Second language learners in CBLT should use the same instructional materials as students who are already proficient in the language of instruction.
“There is an important place for simplified or modified materials in the CBLT classroom.”
CBLT is effective mainly because it allows students to spend more time using their L2.
“The amount of time available for learning is one of the best predictors of outcomes in language development. (…). However, increased time is no guarantee of success, nor is it the only reason for the success of CBLT. Other benefits of CBLT include the motivational effect of using the language for genuine communicative interaction, focusing on topics that are of importance to a student’s education in a greater variety of pedagogical activities, for example, group-work and project-based learning. CBLT also typically leads students to come in contact with a substantially larger vocabulary and range of language patterns and registers than is the case in regular foreign language instruction.”
In CBLT, teachers should sometimes use the students’ L1.
“It is best for teachers to use the L2 consistently and to use a variety of strategies to aid comprehension. Teachers should avoid ‘running translations’ that can teach students to wait for the ‘easier’ language. This does not mean, however, that there is no role for the L1 in students’ personal or academic development, especially during language-focused learning activities (Goldenberg, 2008).”
“The notion that students in classrooms where the L2 is used to teach subject matter can reach native-like levels of L2 mastery in a matter of months is based on a lack of understanding of what it takes to acquire a second language and what it means to develop a deep understanding of academic information and ways of thinking about that information. It is clear from the research on CBLT in classrooms around the world that students and teachers have to work harder than their peers to accomplish the dual goal.”
Here is the book: