Research has figured out that grammar is the wrong thing to focus on in a classroom. There are better ways to teach in a classroom that work. However many schools are not following the latest research so you need to find a good one.

grammar is good in the classroom - but not until every lesson gets you thinking so that is why I do X. If you are not used to the grammar don't learn it. So don't start until you have had around 50 hours in the classroom.