Genghis the Engineer's point about 3 deg is a very good point..not once during circuit training do you ever worry about 3 deg. How would you ever know and how would you expect someone learning a circuit to be able to cope with that.
KISS! is the number one rule..
Ask them what do they know about a circuit..you never know the student might be an electronic wizard of 30 years experience..a circuit to them will be completely different..this allows you to assess the initial ability of the student..then again they may know quite a bit about flying a circuits..
Could follow up with a why do we do circuits..Has the student seen a vfr chart or aerodrome chart/plate?
outline the objectives of the lesson..by the end of the day you will be able to do this ...blah blah.
break the lesson up into sections..writing stuff up on a whiteboard is good because it stays in the students view and they can absorb more information (They might be afraid or hesitant to ask questions)
Ask questions..reaffirms knowledge from previous lessons.
Intro
Objectives
Considerations/POF
Aircraft Management..flaps..power..speeds
Human Factors - stress..lookouts..fatigue..visual factors(runway perspectives)
Lessons breakdown - first i'm going to demonstrate to you a normal circuit..remember to keep your hands on the controls and follow me through..here's a high approach and here is a low approach..notice how I used the power differently.
you could introduce xwinds..extending downwind..orbiting..go arounds as a circuit consideration lesson..
Base turning final (about 500ft)
Turn final..assess the approach, select the aiming point (Use either point and power or pitch and power) get that centreline..assessing the xwind(Maybe)..
short final make a go-no go decision on the landing.
Assessing the profile is a biggy as it changes the power requirements so as Genghis the Engineer has said you need to decide on the approach method for power and speed. I like power and pitch but I have flown with others that like point and power.
Here's what we use
CAA Flight Instructor Guide ? Circuit Training: Circuit Introduction
good luck