Cayce Corley, 5th Grade Teacher

Subtraction on a Different Level

New discoveries happen every day in all different places all over the world. Sometimes in the most remote and unlikely places. School is no different. Discoveries are made here every day by our future thinkers and leaders. Cimarron Elementary is a place where we push our kids to think for themselves, and to think outside the box. We welcome our students to seek new ways of doing things and processing their thinking. One of our students in 5^th grade has done just that. Roman made an awesome discovery with subtraction. He connected a strategy that we learned with multiplication and tied it to subtraction through a classroom number talk. Number talks are tasks we do in class to help students with their mental math and number sense. Roman showed the class his thinking on the board with how he subtracted the two 2 digit numbers. He did the following:

                                       

And to our amazement it worked!!! It really did. The kids became very excited as did I. I began to try other problems to see if it worked. And it did over and over again. I even took it to another level and tried a larger number (a 3 digit minus a 3 digit). To my surprise again, it worked and was even like a brain teaser puzzle. I found that there was a pattern to what numbers you put together, and how you manipulated those numbers with addition and subtraction. It worked with the same pattern every time to get the answer of the problem given.

Interview with Roman

Q: How did you come up with this strategy?

A: Well, I knew it (the array strategy) worked with multiplication so I thought; “let’s come up with a bigger number and minus the smaller number”.

Q: How did you feel when you made this new discovery?

A: At first I thought, “Oh, No! It’s not going to work!” But a class mate came up and said, “It actually works!”

Q: Is there anything else you can tell me about this experience?

A: It felt pretty good. I didn’t think it could possibly work, but it did!

I am very proud of Roman and his efforts to use his mental math skills and to try new things. You never know what students can and will discover with numbers and Math. Students need the opportunity to do this type of thinking and processing of numbers in their own way. Our students are our future, and we need to let them shine in their own ways through their exploration with different strategies and ways of thinking in Math, because you never know what will be that next new discovery!!!