Comment by trod1234

I included the water pipe analogy for electric theory, that is one specific example.

Also, In Algebra I've seen a flawed version of mathematical operations being taught that breaks down with negative numbers under multiplication (when the correct way is closed over multiplication). The tests were supposedly randomized (but seemed to target low-income demographics). The process is nearly identical, but the answers ultimately not correct. The teachers graded on the work to the exclusion of the correct answer. So long as you showed the correct process expected in Algebra you passed without getting the right answer. Geometry was distinct and unrelated, and by Trigonometry the class required correct process and answer. You don't find out there is a problem until Trigonometry, and the teacher either doesn't know where the person is failing comprehension, or isn't paid to reteach a class they aren't paid for but you can't go back.

I've seen and heard horror stories of students where they'd failed Trig 7+ times at the college level, and wouldn't have progressed if not for a devoted teacher helping them after-hours (basically correcting and reteaching Algebra). These kids literally would break out in a cold PTSD sweat just hearing the associated words related to math.