Case
Writing down sentences

Not every teacher is going to be fluent in another language. Now, when dealing with a student that barely speaks English, but could read a good amount of it, would the best thing to be is write it down so the student understands what you are trying to say?

Solution #1
I think that is a good way to communicate. However, I would also try and see if the student comprehends what is being written/read. If not, then another way to communicate is to use a translator in dire situations.
Solution #2
Based on what I thought this prompt was while reading the title, writing down simple but important English phrases on a whiteboard or notecards for the student learning this language could maybe become a good idea.