(and ESL/EFL/ESOL teachers) often say things like this quotation from
the student's version of the Comprehesive Grammar of the English Language
That is, when we draw timelines to explain verbs and time we are probably talking to ourselves rather than helping the students out very much. Teachers often reply to this statement with something like "But my students seem to understand the timelines when I draw them." And I reply something like "Students are so sweet to us...they smile and nod and make us think they understand. Some of that agreement is self-protection, of course, because students generally do not like to admit that they do not understand what is going on in class; some of it is culturally based ways of handling teachers.
But, you probably say, if we don't use timelines, how do we explain time meanings for verbs?
Perhaps the best answer is that we're doing too much explaining and not enough showing. Explanations tend to be abstractions that maybe help a few students. What most learners need is less abstract information and more concrete examples.
Grammar lessons and materials are made up of the Three Big E's: Explanations, Examples, and Exercises. Students need good examples (remember that list of what makes an example good**) and they need lots of activities to try out the language and to help them get a feel for how the verbs are used in communication.
send me your questions and comments at firstname.lastname@example.org.