 The two most common usages for the present simple tense are habits and routines as well as general facts and truths. Our example of routine would be I teach every Monday. We've used our subject I, our base form to teach, and every Monday speaking about the routine that I have. We also have our general facts. The sun rises in the east. Here, the sun would follow under the pronoun it, so we've had to conjugate our verb per our pattern and finish our sentence. We can also talk about general truths, such as likes or dislikes. I like football, or he likes football. Of course there are other usages, but these are the two most common. For following usages that aren't as common, perhaps you won't be using them in the classroom as often. You can have a look in your materials.