Checkerboard. I think you need to sit down and have a nice cup of tea, because you are getting a bit tetchy and resorting to sarcasm. Deehav made a perfectly good point as far as the general application of the Jacobson flare is concerned. His post said "Remember it is how you handle the corrections, not the initial flare, that sets the truly skillful operators apart."
I would agree entirely with deehav. The flare is rarely the problem. It is the gyrations after the flare ie drift, balloon,yaw etc, that causes most concern with ab-initio students. Certainly you should not have to resort to statements of mathematical angles to teach someone when to flare in a C150. Just quietly say, "Watch how I do it, Bloggs and follow me through please" As someone said in an earlier post, students have learnt to land au natural since flight began.