When teaching the present progressive, or continuous, tense, we often concentrate on structure: you have a subject, followed by the auxiliary, “be” followed by the “-ing” form of the verb. A lot of teachers have started calling this verb “the –ing verb”, and rightly so, as I am convinced that virtually nobody can say for sure what the correct term for it is.
Would you call it the gerund? No, because the gerund is the noun derived from a verb, not a verb itself. Here we have a completely different discussion, and another lesson to prepare. You probably do a free time/interests lesson where you ask the question “what do you like doing?”. Your students have the opportunity to practise real gerunds, as in sentences like, “I like playing football, going skiing, painting, reading, shopping...”
You, of course, as a serious ESL professional, know that in a sentence like “I am having a shower”, the “-ing” verb is actually the present participle. How sure are you about that?
participles or adjectives?
If I say, “I am tired”, I know that “am” is the verb and that “tired” is obviously an adjective, given that “to be” is a verb of state, and an adjective is used to add detail to a noun, in this case a pronoun, “I”. But tired is also the past participle of the verb “to tire”. Just as past participles can be used as adjectives, so can present participles: The match was tiring, this film is boring” etc. Expressions like “running water” or “travelling salesman” contain “-ing” adjectives.
When saying “I am” we are invariably talking about a present state, so what’s the difference between “I am tired”, and “I am working”? To say “I am working” also indicates my present state, even if technically speaking “working” is the present participle, not an adjective. Interestingly, in French there is no present progressive tense, they use an adjectival phrase which translates, “I am in the process of to work”. A fine line indeed between adjectives and participles!
All these thoughts have led me to believe that they should not discussed with your students, being indeed pointless grammatical debate that will not help them one little bit to communicate more effectively. Instead of trying to have your students build sentences from pre-defined parts, i.e. aux + verb+ing = present progressive = something happening now why not make a mind map of all the possible things we could say starting with “I am”. After all, “I am English” is a present, just like “I am working”. You could brainstorm emotions, physical condition, nationalities, age, jobs, and what is happening now. This way, rather than focussing on meaningless grammatical structure, you are giving your students functional language that they can use outside the classroom.