Don't let them know you can speak Russian!

I'd been told this before many English lessons provided by private organizations. I'm not going to talk about the advantages and disadvantages of using L1 ( students' first language) in the classroom; I'm taking you through the consequences of disrespectfully attempting to cheat students.

Why do lesson providers host/hire teachers who don't speak the students' mother tongue?

I've asked this question many times at many interviews and the answers varied but all had quite common reasons: schools falsely assume that a non-native speaker will magically force the students to speak English, given they don't have any other means of communication. Another reason may come from the fear of the teacher using L1 as the language of instructions. A sane person would argue that high-quality teaching and language acquisition have nothing to do with adopting this approach.

What are the dangers of lying to students?

I'm not against hiring teachers who don't know students' L1- it's totally acceptable and normal to do so. Although knowing the students' L1 is an advantage, I won't discuss it in this post. The problem is that pretending you don't know the students' language may put you in unnecessary trouble. I tried many times to fake it, but I couldn't keep it for a long time and replied (in English) to students' questions (when they asked in L1).

Firstly, students may feel cheated the entire time and then start to question the integrity of the course provider. Secondly, ignoring students' utterances when addressing the teacher is irresponsible since the teacher doesn't respond to learners' immediate needs, including going to the restroom.

In fact, such a strategy, in my opinion, does the exact opposite: it doesn't motivate learners to communicate in the target language; instead, it either shuts them down or forces them to use a mediator (a strong peer-student), who is in this case the one who benefits. When I was learning Russian, I always felt more comfortable with teachers who knew English or some of English than those who knew nothing. In fact, I was even more terrified to communicate with those who couldn't speak English because I knew they won't be able to answer my questions or be useful when I didn't know how to say something in Russian.