Present tense forms - easy explanations

[beaconsfield]

Dear All,

grateful for help on explaining to a would-be TEFL teacher how best to explain the difference in function between I sit down and i am sitting down (for example) - if this is the wrong place for this thread I do apologise.

Kerry

[Tdol]

I am sitting down- this could be used for the moment the person is lowering themselves into the chair or for when they are on/in it.
I sit down- doesn't refer to now, but to an action that is repeated- I sit down at 9am, turn on my computer = habit/routine

[GoTeacher]

I like to apply these two functions using schedules and roll calls. For present tense (statements of routine), schedules are a great fit. Students can discuss what they or famous people do at certain times of the day. For present continuous (the "now" tense), I like to use a roll call. Instead of calling at the names of your students, though, I call out the names of people who aren't there:
Teacher: Is Madonna here?
Student: No, she isn't. She is ______ing now.