I'm taking this math class at Winthrop! It's really cool...we are doing some very hands on math activities every day and I LOVE it! I can't wait to teach my students some of the things we've learned in this class.
One of the coolest things we've learned is called chisombop. Are any of you familiar with this? I didn't know it was called chisombop...I just thought it was a 9s multiplication tables trick. It's when you number your fingers and thumbs from left to right...1-10. Then you fold down the finger that corresponds with the number you're multiplying by 9. The number of fingers up to the left of the folded finger is the tens and the number to the right of the folded finger is the ones.
In this picture, Sarah's fingers will be numbered 1,2,3,4,5,6,7,8,9,10, from her left pinky all the way to her right pinky.
In this picture, Sarah's #3 finger is folded under. The multiplication problem would be 9x3. Look at the number of fingers unfolded to the left of her #3 and count them. You should see two. Now look at the number of fingers unfolded to the right of her #3 and count them. You should see seven. The fingers to the left of the #3 represent the tens and the fingers to the right of the #3 represent the ones, thus the solution to the multiplication problem 9x3 is 27.
This works with all the 9s multiples up to 10! How cool is that?
There's another one that I learned that's even cooler, but it's way more complicated and will take another post.
Thanks Dr. Mink!