Emily, you can control all dSLR cameras’ shutter speed and the aperture.

What do you mean, teaching photography? You’re still learning–don’t expect to teach anyone until you have years of experience. A brand new pilot does not teach another person how to fly-yet.

Any dSLR will do. What you’re referring to would be one that costs like $3,000 at least without a lens and that is what you don’t need at this time.

canon is the way to go. i don’t know how much you are willing to spend but this is a great camera for the money:

i hope this helps