This is the method we typically learned in School. It has been improved into the ICO order in the last years.
The technique starts by brushing the chewing surfaces, then brushing the outsides and finally brushing the insides. The insides are brushed red-to-white, while the outsides go from brushing, to circular motion, to red-to-white and finally the Bass method, that then is also applied to the insides. These methods are learned as the kids motor skills improve.