Ok, my book had a lesson on Supply and Demand and here is a lesson on it. You may want to add more questions, because some of my classes where faster or caught on quicker so I had some time left over and played a listening bingo game. The dialogue in the slides is from the dialogue in my book. You may want to change it to the dialogue from your book, if you have a supply and demand chapter.
Remember to check the slides and the worksheet.