It’s typical for interviewers to make this request at the start of the meeting. They want to know what you consider important enough to mention. It is difficult to know just how much to say, because you want to highlight all your abilities and experiences but avoid rambling on. Definitely prepare this answer beforehand, so that you are not randomly recalling résumé bullet points on the spot and debating which ones to bring up. Restate your name, your certification, and the school you attended. Talk about the teaching experiences you consider important and relevant (student teaching counts!), and end with a short sentence about the reasons you want to teach in this particular school.