I wouldn't say that adults have 12 years of bad habits - how you do an equation isn't as important as understanding the equation. I've found that if you teach k

I wouldn't say that adults have 12 years of bad habits - how you do an equation isn't as important as understanding the equation. I've found that if you teach kids the "speed" methods right off the bat, they don't fully understand the methods behind it and instead see it as a set of rules and tricks to follow. Think of it like learning how to take the derivative of an equation in calculus - you'll never learn the fast tricks right away because you wont properly understand what you're actually doing if you do. However, after you have this foundation you'll often be taught much faster methods of arriving at a derivative.