We provide scientific method of teaching to make it easier in the classroom.
An abstract system of rules whereby a person's mastery of their native language can be explained (adapted dictionary definition)
Different dictionaries define 'grammar' in different ways but they all effectively talk about the rules of the language. We don't think it really matters what definition we give the word, anyway, as we all have an idea in our minds of what the word means to us. However, do not assume, as many do, that 'grammar' equals only 'tenses', or verb forms (e.g. present perfect, past continuous/progressive). Grammar is language and how we use it; tenses are just a fraction of our language.