Percent with Base Ten Pieces
We draw on students experiences with base ten numeration to dig into percentage concepts and applications. Base ten pieces make conceptualizing percent concepts meaningful to students and allow them to explore percentage in a familiar setting.
The 10 X 10 square mat is the basic model for percent quantities:
Once we have had some experiences modeling various percent collections, we can begin to attach some more information to the model. For example, if the 10 X 10 square has a value of 400 (that is, 100% = 400), then what is the value of ten small squares (or 10%)?
We can now determine many percentages of 400 by thinking about the 10 X 10 mat. What is 28% of 400? 17%? 35%? It's easy to see what the value of each percentage is - the computations are simple! We can change the value of the mat to any amount, 300, 650, 225, etc... and determine various percentages of the values using the model.
We can also work the other way. Suppose 6% (6 small squares) of the mat has a value of 24. What is the value of the whole 10 x10 mat?
Explore these situations for more practice:
The next step is to apply the model to some situations and see what other information we can determine about them. Here are some we explore in class:
These are just a few of many percent situations you might encounter. Take advantage of situations in everyday life to discuss percentages with your child using the models they have explored in class. Very often, it becomes a matter of mental arithmetic and estimation, and it gives students a sense of mathematical power when they can make sense of the percentage examples they see on a daily basis.