The thought that using L1 (mother tongue) is usually shunned by English-teaching institutions around the world, who say that students should be in an environment with constant use of the target language, the goal is to provide the maximum immersion experience possible. However, even though I see the point in doing so, ignoring L1 in class provides for more disadvantages than advantages.
I do belief that if you’re in a class with students from many different countries, there is no other option because their mother tongues are too different and diverse and English would be the common ground for all. Most English classes around the world, however, are for people from the same city, all of which share similar backgrounds and culture, as well as their teacher. And sharing characteristics accounts for an advantage the teacher has over teachers of multi-language students.
First, L1 can be used for quick translations in situations where time can’t afford to be wasted, such as helping students carrying on a conversation they are very engaged in.
Second, there are common mistakes made by students precisely because their dependence on their mother tongue that need to be addressed, Brazilian teachers will understand this if I mention the mix-up their students make between “have” and “there be”. Situations like this are proof that L1 can’t be ignored in English classes when they will help students figure out things about their target language more easily.
Also, L1 is a fantastic tool for beginner levels. We must stop ignoring the fact that every person starts learning a new language by translating things in their heads, and translation can come as a great starting point if dealt with properly. It is a way for teachers to ensure that students grasped the correct idea behind using a particular structure and it helps in making sure students understand what they have to do.
Finally, students are individual people with personal needs. Some of them need their mother tongue to feel more confident about their learning. They might use it to compare different ways that ideas are conveyed in L1 and L2, they may use it to learn vocabulary better, or in any other way they feel they learn more effectively.
In conclusion, teachers are always on the lookout for better techniques to help their students, and using L1 in class is an effective tool that can no longer continue to be ignored.