Fun thread.
The actual problem was lost in the scrum, though (not unusual for this bunch
)
The real problem is that the person who wrote that question of performing multiplication by repeated addition does not understand the Law of Commutation and the kids do.
Look here for those who have been out out school too long:
https://www.mathsisfun.com/associative-commutative-distributive.html
Now the issue was they had to show how they get 5 times 3 through repeated addition.
The test writer wanted them to add five sets of "3" together.
The kids being smarter than he/she added three sets of "5" (quicker and easier)
The Law of Commutation says either way is correct - and the KIDS knew this.
So, they got marked Wrong for the order in which they did the additions.
If the test writer had known mathematical symbols he/she could have forced the order of operation.
He/she didn't and so half the kids did it the easier way (the smarter half of the class)
It was the idiot 'adults' who failed, not the kids.
And as far as New Math, my children went through that disaster. My kids did just fine because I made them do their homework (in front of me ) twice. Once the New Math way and once the correct way - correct in the old readin/writin/rithmatic and gazintas sense.
And as far as 'estimation' that osme are sneering at - if you don't have a sense of what the magnitude of the answer should be then you will accept anything the calculator grinds out - and that is the point of Hennings comment.
I still advocate that children should initially be taught mathematics first using tables of logarithms and a slide rule.
Why?
Well, not because I am a curmudgeon - rather because it gives them the ability to at least look the powers of the numbers about to be manipulated by the calculator and by adding and subtracting the powers in their head, know almost instantly that the result will be in the 10^4 range (for example). If the calculator spits back and answer in the 10^5 or 10^7 range then you know immediately there is a problem
99% of the kids coming out of high school today cannot do that - and that is a real shame-on-us who are the adults in the room.