Why Would a Math Teacher Punish a Child for Saying 5 x 3 = 15?

[muriel_volestrangler]

440. The first question is about the repeated addition strategy

and the student came up with the correct answer, using repeated addition.

I don't think people get 'hung up' by the phrase 'multiplied by', later on. So since the kid reads the question as 'what is five multiplied by three' or a paraphrase of that, and writes down a five and two repeats of it, with plus signs in between, they appear to have understood the repeated addition strategy.

Again, do you think using the phrase 'multiplied by' causes problems in mathematics?

For the array question, I understand the convention of how to give the size of a matrix is important, and if asked for an 'array' (a word I don't remember using in maths, as opposed to computing, but maybe they do now), there might be advantages in being strict about following that convention, even when you're not dealing with a matrix yet. But such an approach can frustrate a kid who understands the principle behind the method you've taught, but has only been told "there is a reason for always using this order, but I can't explain yet". It is, to them, rote learning without a justification.