Possible for a teacher to teach without combining English with mother tongue (first language)....?

in my opinion, it is not possible for a teacher to teach English without combining English with mother tongue (first language). Because, it will allow students to understand what is meant. Although, he is teaching with the English language. But he would always add the main language on the sidelines saying.
Because sometimes there are language or terms that are difficult to understand by students and there is no equivalent in English. Such as the names of traditional foods and certain sayings.

For Example, in English classes. Sometimes the lecture combine an Indonesia language in his subject when he explains. It is intended for students who do not quite understand what is explained in English, can understand.
A similar thing happened to a teacher who teaches English in children and kindergarten.
They combine English language with the mother tongue because the child is still difficult to absorb the words in the English language.