The ability to think flexibly among numbers is the basis for mental math and computation in general. My students in Grades 2 and 3 love to play a game called Banker, Builder that deals with composing and decomposing numbers. It starts with a set of numeral tents. I'm sure this is not a Manitoba-only activity, and yet I cannot find them online anywhere except MB sites, and I used the set from the Hands On Math series, which is published in Manitoba. Go figure. Click here to access the Place Value tents from Manitoba Education.
So to use these tents in the game I might ask the students to choose the number tents they would need to "build" the numbers 56 and 38. The Builder asks the Banker for the tents that are needed (see above). Then put the ones tents on top of the tens tents to build 56 and 38. I want the students the combine these two numbers - add them together. The Builder can request other tents from the Banker to do so. So the tents are pulled apart again.
The Builder might say something like: "Can I trade the 50 and the 30 for an 80?" The Banker then hands over the 80 tent. Now the Builder looks for aother two tents that can be combined, such as the 6 and the 8. "Can I have the 10 and the 4 to make 14 please?" The Banker takes the 6 and 8 and trades them for the 10 and 4.
Now the 14 tents must be pulled apart. The Builder can now combine the 80 and the 10 to make 90. There is only a 90 and 4 left, and to combine these two cards, put the 4 on top of the 90 to make the number 94.
And that's how 56 + 38 = 94! Activities such as Banker, Builder really helps kids visualize the actual decomposing and rearranging numbers that is necessary for adding with regrouping.
Travelling Curriculum Support Teacher