Why Is Everybody Screaming on Facebook?

Why is everybody screaming on Facebook?

Or, How I learned to stop worrying and love the Common Core

One of my all-time favorite rants on Facebook concerns the new Common Core standards. First, a disclaimer, I am not an expert on the Common Core, but I did teach the math that these folks are screaming about, so I feel that I have a right to offer an educated opinion.

The offending math problem looks like this: 32–12 =? Every adult in the nation says, “Well that’s easy. Subtract 2 from 2 and 1 from 3. The answer is 20.” Then they show the way second grade students are taught to solve the problem: Here’s the solution shown.

12+3=15;

15+5=20;

20+10=30;

30+2 = 32

Add 3+5+10+2=20 so 32–12 again equals 20.

Facebook friends scream that this is insane. Their method is much easier. It sure does look simpler, doesn’t it? Obviously, the Common Core method is ridiculous. But when asked why their way works, many adults might not be able to explain.

Let’s put it another way. Suppose you buy a cappuccino that costs $5.33. You have a five and a one. You give them to the barista and count on him giving you the right change. You are expecting two pennies, a nickel, a dime and a half-dollar (2+5+10+50=67 cents). Hmm, seems like you just made the same kind of calculation in your head. Probably none of us would sit down with a piece of paper and subtract with all that regrouping.

This is common sense to us, but not to kids. We learn this as we develop number sense. The new process that freaks everyone out makes much more sense when explained this way. And, surprise, surprise, the offending method is NOT proscribed by the Common Core. It is just common sense.

         

Try the same process of counting up using an equation where you would have to regroup (the bane of many students’ lives).

Let’s say, 41–23=?

So 23+7 =30;

30+10 =40;

40+1 =41.

7+10+1=18 -- the very same answer found with adults will find with the much more complicated regrouping process. Kids don’t tear their hair out, and as an added bonus, they learn that addition and subtraction are complementary processes.

To go back to the original scream-invoking equation (32-12=20): How many remember that 3-1 is really 30-10? This concept often gets lost when we just do the process. How about a really hard problem, like 2,000-899=? What a lot of regrouping! Numbers might get lost in the shuffle when solvers jump from place to place. But add this simple step: subtract one from each number.

2,000-1=1,999

899-1=898

This changes the equation to 1,999-898=1,101.

It gets a lot simpler and surprise, surprise, the answer is the same. Get out the calculator and check.

         

These are just two of the ways which are shown to students for solving problems. They are also taught the “old” process as yet another way to think about math. They then choose the way that makes sense to them -- and when kids get to choose, they LOVE math. Do you?

         

So you do it your way and the kids will do it theirs and we will all get the right change, find the right answer, and enjoy a refreshing drink at the well of math. Take a deep breath, think about it, and please, don’t shout at me on Facebook.