What has two wheels and one working arm and leg?

If you answered the riddle with this semester's English teacher, you're right. (By the way, I'm the one in the middle.) The truth is I recently broke my right wrist and my left ankle, and so I'm temporarily left to communicate with you by typing with my left hand. I am on the mend, though, and hope to be back in the classroom in a couple of weeks. In the meantime, you'll be starting your high school journey without me. Please do the best you can. Listen and learn from from your current substitute; he is very well read and has traveled extensively. You are lucky.