We’ve all seen those pictures making the rounds of children’s common core math homework that makes it look like some sort of crazy, complicated way to do basic math equations. If you’re like me, you grew up before common core. We memorized math equations using tables, because it was the most efficient way to get the answer to a math problem. Memorizing the tables allowed you to immediately know 12×12=144. Unfortunately, you also didn’t have to memorize anything that didn’t fit in the table. This is why I can ask you what 34 x 28 is, and say with some measure of confidence that you will either have to scratch it out on paper or use a calculator. Children who have mastered common core math will be able to do that equation in their heads in seconds. Why?
From the beginning, our children are learning numbers with ten frames, number bonds, and other highly visual methods of number comprehension that break down equations into simple parts. They aren’t just memorizing algorithms, they’re learning how to manipulate numbers in their heads to find answers to math problems. While in these early years, we’re still teaching children basic equations (2+2=4 is called a “standard algorithm” in common core), we’re also giving them a depth of understanding that wasn’t there before common core math existed.
You can do these equations in your head: 30 x 20 = 600; 30 x 8 = 240; 20 x 4 = 80, 8 x 4 = 32. You can easily add the four sums in your head, too: 600 + 240 + 80 + 32 = 952. But the way you were taught math, you don’t instinctively know how to break 34 x 28 into those four equations to get the answer mentally: 952. Here’s how they teach it in common core, using what’s called area model math:
Break it down! 28 = 10 + 8 and 34 = 10 + 4. Here’s the area model for the above equations:
34 x 28 = ?
20 | 8 | |
30 | 600 | 240 |
4 | 80 | 32 |
34 x 28 = (30 + 4) x (20 + 8) = 600 + 240 + 80 + 32 = 952
It’s a nifty party trick to be able to do big equations using mental math, and it’s also the one of the many goals of our common core math curriculum. Our children are going to be math wizards!