This STAIR was very informative. The graphics made it engaging and your explanations were very clear and easy to understand. It might have been helpful to have a back arrow on the pages as well because there were times when I wanted to reread what was on the last page but could only go forwards. I thought the quiz questions did a good job of giving the learner practice using estar and ser.
Sometimes when I got a question wrong and clicked try again it took me back to a previous question instead of the one I got wrong.