Photocopy "cheat sheets" before your presentation with the most common functions you would like to cover. For example, if you are going to be demonstrating how to graph equations on the calculator, make sure your cheat sheet shows the exact steps and buttons to push. That way, if you get a little ahead of the class, they can refer to the cheat sheet instead of having to ask you to repeat the steps.
Place your calculator on the overhead projector and ensure a clear image is shown on screen. If the image is out of focus, turn the focus dial until the image is clear.
Perform the first step on your cheat sheet, and wait for everyone in the class to perform the operation and look up. For example, to enter an equation, hit the "Y=" button (a blue button in the top row).
Once you are sure that everyone has performed the same step, move onto the next step. The next step on the TI 83 to graph an equation would be to enter a function into the Y editor. For example, to enter the equation "x-2," press the following buttons: "x," "-," and "2."
Repeat Step 4 until you have completed the items on your cheat sheet.