### Number rainbows to learn subtraction facts

I thought some of you (those who teach second grade) might enjoy my NUMBER RAINBOWS. The idea is that you connect two numbers with an arc if they add up to the particular number, such as 13.

Then, the child can use it as a reference when subtracting from 13 or when doing subtraction drill. You could first drill subtraction facts WITH the rainbow (such as 13 − 4, 13 − 7 etc.) and then without.

You would also ask the child to reproduce the rainbow - and color it, of course! These make for quite pretty math facts practice, don't you think!

I'm going to add these to my Add & Subtract 2-A book.

mathmom said…
This is awesome. I just got pointed here by Denise at Let's Play Math. I love this idea!

Once your kids learn how to multiply, think about taking this one step further and showing them the Gauss Method of adding up a sequence of numbers. (My post is about teaching this to middle schoolers, so I use more complicated problems and go into deriving the formulas, but I've taught the basic idea to kids as young as 3rd or 4th grade before.)

You have a great blog here. I'll be sure to keep my eye on it. :)
Maria Miller said…
Thanks, MathMom. It's quite natural to connect this to Gauss' idea. In fact, maybe my familiarity with that somehow subconsciously helped my brain to produce this idea... though the main input was my daughter's struggles in remembering the facts.

Also, now that I look at the pics, I realize I should have drawn a SUN in the corner instead of a square (with the number in it)!
Shirley said…
hi... my first grader loved this! I am so glad I found this in time for 'friday fun' for her! We did them on pages with princess castles on them to make it even more appealing to her.

I also was inspired to stretch it a bit for my 3rd grader - we listed out the factors for a number, and then she put those in numerical order along the bottom and connected them to make the rainbows! She loves to color and loves math so this was a double goody for her! She did all the ones she knew so fast and wanted to do more so she could have more rainbows...