What I usually do with my students when we need to revise/introduce the present perfect form is to make a circle with them and I start in the middle of it with a ball. The students form the circle and I start asking one question using the form "have you ever....?" and I throw the ball to one student at the same time and he has to answer. the student that doesn't answer correctly is out of the circle.
I have also used it for the form There's/there're by asking them " is there a yellow car in the class/are there 3 red crayons in your pencilcase?...as examples.
4)With these kind of activities I give importance to the productive grammar practice, I want my students to realise that the good use of the language is important so as to have a good communication but without even knowing which grammar topic they're dealing.