a box and then draw a heart around"'s" and another heart around "ing" and say that this is the tense and we use it to show that something is happening now.
later when someone says something like " i am play the piano" i simply ask what's missing and the class answers the second heart and the person who made the mistake can correct themselves.
but then they have to learn how to answer those questions and i revise them each class in the beginning until almost everybody can manage an answer.
in this way by the end of the year they have a stock of questions and answers in their memory that 