Do you cringe when a student declares "cross multiply!“ as soon as they see a problem involving fractions?
It doesn't matter whether you teach elementary or high school, whether you're a parent or a tutor, having a student yell out a trick without stopping to think is painful.
This book is filled with alternatives to the shortcuts so prevalent in mathematics education and explains exactly why the tricks are so bad for understanding math.
Nix Cross Multiply (Fraction Division):

Instead have students practice
dividing
with common denominators until they
see the shortcut "multiply by the reciprocal."
Download the Book for a full explanation.
with common denominators until they
see the shortcut "multiply by the reciprocal."
Download the Book for a full explanation.