Turning error is liniar. From 0 deg. error at East or West, add 10 deg. error for each 30 deg. towards North or South, giving a final 30 deg. error at North/South.

Strateandlevel ! ' The compass needle is pivoted North of the C of G to counteract dip.' !?!? Maybe I missed something but I thought the Cof G moved from underneath the pivot BECAUSE OF dip.

Deadhead.
Teach : OSUN so you can still turn on the compass without having to divide by 3.You'll find a lot of students struggle to subtract 250 from 030 when they have their hands full of aeroplane.

How much approximately to under/overshoot by depending on lattitude.

Stuff like sluggishness, swirl, momentum of the CofG to the outside of the turn is for expensive written exams only.

Make sure the student understands a) that because the markings he reads are the ones facing him, the north-seeking edge of the compass is actually the one with the "S" marked on it, and b) that because the lines of magnetic force go around the earth and into the pole and out of the poles that the north seeking end of the compass is being pulled both north and down (up in the southern hemisphere).

Now balance a small bowl upside down on the eraser end of a pencil. Accelerate the pencil forward. Observe which way the bowl tilts. If you think of the part of the bowl with the "S" on it being pulled upward or downward, as appropriate to your hemisphere, you will see that if the plane is flying on an E-ish or W-ish heading the bowl will turn.

It's too bl**dy difficult to turn on a cr*ppy gadget like an airpath. If you have to and you can see a the horizon, pick a point roughly in the correct direction, turn towards it, fine tune when the compass has settled.

Demo turning and acceleration errors once by all means, that should convince the student to use the above method.

Keep it simple, and save the theory for the ATPL Nav exams.

And if IMC, time the turn at rate one.