This is how I help students to remember the formation of the present progressive tense. I design on the board the three parts of a hamburger: the upper bread will be the "am, is, are" part, the burger stands for the verb and the second piece of bread will be the "-ing" form. I have made a really impressive hamburger and put it somewhere in the classroom. Whenever they forget to use either am,is,are or -ing, I point at the hamburger until they get used to it. They always make their hamburgers which we use to decorate the classroom... Later on I add a plate on which I write the word "now". That's what I point at when they get confused while using Pr. Continuous and...Simple Present (for example).