 The two most common usages for the present continuous tense as it relates to speaking about things in the present. We have actions in progress at the time of speaking, specifically right when it's being said. So, I can say, I am teaching right now. However, we also have actions in progress around the time of speaking. I'm reading a good book. Now, of course, I'm not reading a book just now, but I started reading a book in the past. I am reading it perhaps today, sometime, and I'll finish reading the book at some point in the future. Again, I'm not doing it just now, but around the time of speaking.