@aeveltstra
"my kid’s response proves" why we don't try and teach them 3 things at once.
"testing the pupil’s application of it to the problem" - the teacher does that when they mark it.
"The choice you present assumes they aren’t" - does nothing of the kind. Only does what every teacher does and teach 1 thing at a time.
"prior choice to teach your simplest formula" - we don't teach only the simplest formula, but we only teach 1 thing at a time. Composite shapes is a high school topic.