Why Do We Do Math This Way? (Day 10 of 25 Days of School in the Christmas Season)

Posted: November 25, 2014 in Uncategorized

Over the past couple of months I’ve been watching and reading about everyone’s views about the Common Core Math Standards (which I am 100% for but live in a state where they have been removed). Yes, I know we have all seen the uprising of those who don’t “get the new math”. Guess what. There is NOTHING new!Screen Shot 2014-11-25 at 7.14.15 PM

I recently was in a conversation with an educator and I was asked about the multiplication method to the right (73 x 36) and if I had seen it. They also asked me why it would be taught instead of the “normal” way. Well, I asked them why the “normal” algorithm works. I also shared that when students solve the problem using the algorithm they are multiplying 6 by 3, 6 by 7, 3 by 3 and 3 by 7. Then they get confused about adding a zero and why you add a zero and then you’re back to square one.

Why does the square method work? Well, students understand how to multiply 30 by 70, 6 by 70, 30 by 3, and 6 by 3. Then when you have the numbers of 2100, 420, 90, and 18 you can add them together for the answer of 2,628.

The “new” way of math is just helping students understand numbers and how they work BEFORE teaching the algorithms. Ask yourself. Why are you good at math? Is it because you understand numbers or is it because you learned the algorithms and it makes sense? Which is better for students?

I hope mechanics understand my car and how it works a little better than me. I know that if I turn the key it comes on. I know it’s a little more complex than that, but I just don’t understand it.

My hope is to help students understand numbers a little more and not just know it works.

If you want to read some other views about algorithms, read Jonathan So’s post.

Another great view of multiple strategies by Matt Coaty.

You can even check out the Chinese method to multiply.

I know that this is only day 10 of the 25 Days of School in the Christmas Season, but these posts are written on school days. If there is a post over Thanksgiving Break, then it will not be a part of the series.


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