Common Core Math Fail

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According to NBC’s Washington bureau, this is the way to solve a simple subtraction problem using Common Core math procedures. Note that the original calculation requires one calculation — two if you subtract one number at a time from right to left.  Here’s your Common Core math tail for this week:

Common Core Math

Is this really the best way to solve this problem?

The Common Core solution requires seven calculations with numerous opportunities for errors. The idea seems to be to make the numbers in the third column integer multiples of 10 as long as you can. Let me suggest an easier technique:

12 + 5 = 17
17 + 5 = 22
22 + 5 = 27
27 + 5 = 32


Forcing the students to figure out what number to add to 12 to give 20 basically asks them to calculate 20 – 12. Why is that any easier than calculating 32 – 12? This has all the earmarks of math education specialists who always manage to come up with screwball techniques because they don’t know math!

Subject Matter Expertise is Lacking

As many have observed, a major problem with K-12 education is that teachers are trained to teach. They are not actually required to know much about the subjects they teach. It happens I have a first-hand example.

I am professor emeritus of economics at California State University, East Bay. We have a small Master’s program in our department. Decades ago, when I was teaching in that program, one of my students was a high school teacher. She did very well in the class I taught and went on to successfully complete the M.A. After the course was over I asked her if she was going to teach high school economics. She replied, “No. I can’t. My certificate is in business. To teach economics I need a certificate in social studies.”

Believe me when I tell you that things have not improved in the years since that episode. Knowing the course material is apparently less important than acquiring pieces of paper alleging that the holder is able to do something.


The necessary changes will not happen as long as powerful teachers’ unions continue to run the public schools. Charter schools and private schools are two alternatives. I have to point out that charter schools are part of the public school system in California. However, charters have considerably more flexibility in designing classes and hiring (or firing) teachers.

The U.S. is falling behind the rest of the world, especially many Asian countries. Even today, a large fraction of science and engineering Ph.D.’s awarded by our universities are earned by foreign students. Will our politicians wake up in time?

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About Tony Lima

Retired after teaching economics at California State Univ., East Bay (Hayward, CA). Ph.D., economics, Stanford. Also taught MBA finance at the California University of Management and Technology. Occasionally take on a consulting project if it's interesting. Other interests include wine and technology.