This just in: person who already knows how to do multiplication is faster at solving problem than a teacher explaining multiplication to 8 year olds.
It's literally the same steps, just putting them in a grid instead of stacking them.
Like, let's vocalize the "old way"

2*5=10, carry the 1; move to the tens; 2*3+1=7 == 70
Add an X to increment the second value
1*5=5; move to the hundreds; 1*3 =3 == 350
sum the two values; 350+70=420
Break it apart the common core way:

2*5=10
2*30=60
10*5=50
10*30=300

10+60+50+300=420

You're adding four numbers instead of 2, but don't need to keep track of carried values.
IME most people overlook CC's failings of further entrenching standardized testing in a way that exacerbates "teach-to-the-test" policies, and focus on being humiliated by a 4th grade math problem that they couldn't understand because it looked different.
So educators' problems with CC: further encourages teach-to-the-test.

Parents' problems with CC: I was embarrassed when I couldn't help my kid with their home work but I'm sure not going to admit that maybe I didn't learn math very well, it's the book that's wrong.
"God, why do they care so much about *process* and showing your work?! I got the right answer, didn't I?"

Believe it or not, the point of a math class is to learn math, not to crank out some answers at the answer factory.
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