I normally, teach individuals or pairs the maximum is a group of five. My teaching lessons takes place at a cafe or if the student is comfortable enough, then at the place is OK or at a library. I teach using an ipad because I store all prepared lessons on it so I'm well prepared for students. Grammar and word phrasing is important to learn as it is what makes up English as a whole. I might recommend an app for student to learn at least five words every week.