A question I often get when I talk with people interested in teaching English in Thailand is “Do I need to be able to speak Thai to be effective as a teacher?”
My answer to them is a resounding “No.”
When I went through my TEFL training, I was taught to never use the local language in the classroom. I fully agree with this advice.
I’ve discussed this point with many foreign English teachers. Those who speak some Thai and use it in the classroom defend their position by saying: “Using Thai in the classroom saves a lot of time. How could I possibly explain some of the things in English when the students don’t speak it all that well yet?” I always wonder if those teacher have considered that they may be teaching above their student’s level?
A poll at Ajarn Forums back in 2005 resulted in 54 % of teachers saying “Yes, it makes a huge differene,” 23 % of teachers saying “It helps, but it’s not a big deal,” and 23 % of teachers saying “No, it makes almost no difference.”
To be clear, I highly recommend learning to speak Thai fluently to anybody who lives in Thailand. I also agree that it will make a huge difference for English teachers to speak the language well. You will not only be able to build better relationships with your Thai colleagues, but also understand what your students are gossiping about…
Nevertheless, I hold on to my opinion that Thai should not be used in the classroom. Here is why: as I wrote in “Why do kids learn languages so easily?” research suggests that learning words by inference is more powerful than just being told their meaning. In other words, refraining from speaking Thai in the classroom forces your students to use different muscles in their brain. They will discover the meaning of a word based on your pictures, drawings, realia, gestures, and descriptions. Sure, it is a bit more work for you, but the results will speak for themselves, and will make you a better teacher in the long run.