Just to note - てください would be a bit more 'ordering'..i.e. a teacher speaking to a student, whereas てくださいませんか is a bit less direct i.e. the student asking the teacher for a favour. So the student wouldn't say てください to the teacher. Also, remember that ください isn't like the English please as it's more of an order/direction. I used to say ください to my Japanese girlfriends ten year old and I noticed he was looking a bit weird at me so I googled it and went DOH!