Today I taught irregular verbs to group of intermediate grammar students, mostly from China. They have all been here a while but still have such trouble with grammar. The first chapter of the level 3 book skims over simple present and present progressive, like it's an easy review. Well, sure, it's an easy review, but understanding and using are quite different. The verb forms are so messy with "I going" and "I am goes" and sadly some are fossilized. One student went to middle and high school here and said no one ever taught her grammar! In my experience, the longer a student has been in the U.S., the more problems he or she has with grammar.
A student asked me the difference between "arise" and "rise". I looked it up - isn't Google search just wonderful in the classroom? "Rise" is to ascend but it's physical, literal. We had just gone over literal and figurative meanings, since they recognized "hang" in "hang out" and "hangover" more than they did the original meaning. "Arise" means the same thing but in non-tangible situations such as problems, situations, coups d'état, and so on. Who da thunk? I suppose I should warn them that Americans confuse past and past participles. I seen it. I should of did it. I'll let them figure that out later on.