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Monday, November 16, 2015

5th Grade: Confusing the Role of Zero and the Decimal Point

As fifth graders learn about the "behavior" of number systems, they are getting mixed up with the role of zero and the role of the decimal point. They see both as a dividing line, and since the two have a similar circular shape, they get confused as we move from learning about the real number line to learning about place value.

Today we'll directly discuss the difference as we look at the diagram below. We'll start with our start-of-the-year focus on the amazing invention of the base-ten number system, a system that uses 10 digits to create numbers that go to "infinity and beyond."

Then we'll see how each of those numbers includes a number of digits placed strategically to show the numbers value. We'll notice how the decimal point's role is to divide the number into integer and fractional parts. We'll look at how those places are different from place to place and to the left and the right of the decimal point.

Have your students met with this confusion? If so, how have you explicitly discussed the differences? As I read about fractions in the NCTM's latest journal last night, I realized that it's imperative that we clear up this confusion before we move from the study of place value to the study of fractions. Onward.