I'm teaching English to children here in Germany. I got into a discussion yesterday with another teacher here (she is German). I feel like an idiot having to ask this, but she has been teaching children to say "today I do my homework," whereas I would say either "today I will do my homework" or "today I am doing my homework." Is it proper English to say "today I do my homework?" It just sounds wrong to me. I have taught so many students the Simple Present Tense, but I have never taught them to use it in this way.
'Today I do my homework' is natural only of you see this as part of a schedule:
Here is my plan for the week:
Today, I do my homework;
Tomorrow, I revise for the exam;
Wednesday, I tidy my bedroom.
If you are referring to a plan or arrangement, the natural things to say are:
I'm doing/going to do my homework this evening.
If it's an instant decision, or promise or offer, it's more likely to be;
I'll do my homework this evening.
You might find this interesting if you are discussing such matters with your colleague.