Unit 6, Lesson 3
Say It with Decimals
Accelerated 6
Preparation
Lesson Narrative
In this lesson, students use decimal notation to express situations involving fractional increase and decrease. First students see that long division can be used to convert a fraction to a decimal. Long division finds the quotient one digit at a time, from left to right. They recognize that the quotient may be a repeating decimal, a decimal that has digits that keep going in the same pattern over and over, which they learn to express with bar notation. For example, means 1.3333333 . . . . Then students revisit situations where an increase or decrease is given as a fraction of the original amount. They match these situations to equations with decimals. For example, they see that “one quarter less than “ can be expressed as or as .
As students clarify which values repeat in a decimal expansion, they attend to precision (MP6). As students use the distributive property to write equations in a simpler way, they are making use of structure (MP7).
The last activity is optional because it provides an opportunity for additional practice matching equations and situations in a familiar context.
- Comprehend and use the term “repeating” (in spoken language) and the notation $\overline{\phantom{“ “}}$ (in written language) to refer to a decimal expansion that keeps having the same number over and over forever.
- Coordinate fraction and decimal representations of situations involving adding or subtracting a fraction of the initial value.
- Use long division to generate a decimal representation of a fraction, and describe (in writing) the decimal that results.
Let’s use decimals to describe increases and decreases.
Required Preparation
None
Long division is a way to show the steps for dividing numbers in decimal form. It finds the quotient one digit at a time, from left to right.
Here is the long division for .