In the comments section of a language teaching blog following a discussion about correction through recasts, the following appeared:

“I agree with you when it comes to full immersion language programs or any other learning contexts where there is a lot of exposure to the target language. I was specifically talking about classroom teaching and learning.”

Wow. This is very disturbing to me — that someone with good credentials in our field would state that classroom teaching precludes a lot of exposure to the target language.

What suggests that there is not a lot of exposure to the target language in a good world languages classroom? ACTFL guidelines are for 90% or more target language. Surely that constitutes “a lot” when it is truly achieved?

Truly achieved. Does that mean 90% Japanese noise, or 90% Japanese that students can understand? The fact is that many teachers who do their due 90% of TL do not make that language comprehensible. And that means there’s a huge discount operating, since only comprehended language can be acquired:

%-target-language x %comprehensibility = %comprehensible-input

It is the percentage of comprehensible input that really matters. I can provide 100% target language by turning on the radio in Japanese. My students aren’t going to acquire.

How’s your ¬†classroom math? What’s the optimum practical value for %-target-language to maximize %-comprehensible-input?

Consider a teacher who uses all target language, but lacks the skills to make it comprehensible to her classroom of Novice High learners. She might have numbers like this:

100% TL x 15% Comprehensible = 15% Comprehensible Input

Compare this to another teacher who uses English in the classroom 15% of the time. (So, a teacher who is not “reaching” the ACTFL 90% target language standard.) But the reason this teacher uses English is to make the remaining 85% of the language understandable to her students. So her numbers look like this:

85% target language x 95% comprehensibility (she isn’t perfect!) = ¬†80% Comprehensible Input

That’s a lot more than 15%, isn’t it? Let’s imagine that each of these teachers teaches for 100 hours.

Teacher A: 15% x 100 hours = 15 hours CI equivalent

Teacher B: 80% x 100 hours = 80 hours CI equivalent

We won’t even consider the advantages Teacher B will have in classroom management (since students most frequently ‘act out’ because they simply don’t understand the language in traditional classrooms, or could care less about some dry textbook story about Maria going to the biblioteca).

This kind of math makes an enormous difference over the course of a school year. It also shows why it takes so many hours for people to pick up language through immersion — if they ever do. (I get a lot of longtime Taiwan residents studying Chinese with me by Skype. Go figure, if immersion is so awesome.)