3-4 min Presentation for a job interview for the Art Institute

I am ususally good with on the spot selling. Because there is not any "type" of structure. But now, I have to give a 3-4 min presentation on an item. I know what item I will present to sell, but I have no idea how to even begin the presentation. The item I will sell has to do with notes for school children, I am going to bring the notes cards in, there is not allowed any powerpoint presentation, which I would never do any way. They are the so boring to watch. I am a graphic designer, so visual is not my problem it is the talking. I need to know or get some pointers to start the processes.