I teach 5th grade. I had to explain to a student walking in line. He would never walk in line correctly. Finally after correcting him for the 1000th time, he snapped. “What do you mean? What do you mean get in line? What’s the line? Why do teachers always say that?” It never occurred to me he didn’t understand after being in school for years. He was the best though. One of my favorites.
I had a nun who taught us the famous quote 'Vini, vidi, vici'. I was also taught that this is where the evil 666 originated. (VI, VI, VI). It was only after an embarrassing conversation as an adult that I realized it was 'Veni, vidi vici'.
There are teachers - far too many teachers - purposely 'teaching' incorrect things such as sex education in order to further their radical and/or uninformed political-religious agenda.
I had teachers 'teach' us that certain musical progressions etc were 'incorrect'. When I pointed out multiple examples of these progressions in famous masterpieces, I was told that they were exceptions, and that they were still 'wrong/incorrect' etc.
I could go on. But my point is that given the state of teaching, it's no wonder some of the students struggle.
Oh yeah, depending on the age and experience of the student, putting a thermometer in a flame to determine its temperature is not an unreasonable thing to do. A teacher should have covered that before putting students - probably children - in front of an open flame.