Modeling Addition and Subtraction
Using a base five model for exploring basic operations helps illustrate the importance of regrouping in addition and subtraction. The meanings of the basic operations themselves help develop the models. Here's a couple of examples:
First, the addition problem...
Notice that the units had to be regrouped into one strip and two units...
Addition is, quite simply, a process of combining and regrouping!
Now, for the subtraction problem. Here we have two meanings to explore, the take-away model and the difference model.
These simple models will work in any base, including our own base ten. Here are some more problems to try. See if you can picture the pieces that represent the numbers in your imagination.
Our next lesson takes a look at multiplication and division concepts with base five models. See you there!