Fractions, Decimals and Percents Mini-course

Session Five

Developing Decimal Concepts

Objectives• To use paper strips and base ten blocks

as manipulatives for illustrating decimal concepts.

• To explore decimal notation, comparing decimals, and addition & subtraction with decimals.

• To become familiar with the NCTM Technology Principle.

Introduction to Base Ten Blocks and Number strips

• What is the connection between decimals and fractions?

• How might you use money to help your child learn about decimals?

• Number Strips and Base Ten Blocks are also used to illustrate decimal concepts.

Decimal ConceptsDefine each term:

• Decade

• Decimeter

• Decagon

• Decathlon

-- 10 years

-- One-tenth of a meter

-- A ten-sided shape

-- An Olympic event consisting of 10 contestsWhat do these words have in common?

Decimal Strips

• Cut out and label the decimal strips• Label one strip with fractions and one

with decimals (See sample on overhead.)

• What is the decimal name for the spot halfway between 0.7 and 0.8?

• How did you determine this?

Decimal Strips

• Divide the strip into ten equal parts, making 100 parts in the entire strip.

• Where is the mark for 0.75? Explain

Decimal Strips

• Where is the mark for 0.20?

• How does the relationship between 0.2

and 0.20 relate to prior experiences

with fractions?

• Partner up: Person #1 picks a two-digit

decimal and person #2 reads the

decimal using “hundredths.” Switch.

Decimal Strips

• 0.6 versus 0.06

• What is the difference between these two values?

Decimal Strips• How would we name a spot located between

two of the hundredths lines we have drawn?

• What would the numerical notation look like?

• How would we read such a decimal?

• Where would we find 0.437 or 0.291 or

0.58316219?

• What logic is necessary to locate any

decimal on the number line?

At your tables…

Which is Larger?

• 0.45 or 0.71

• 0.8 or 0.24

• 0.05 or 0.5

• 0.734 or 0.73

• 0.02 or 0.020

• 0.5931 or 0.6

SAVE the fraction & decimal strips in

your folders to use again next week!

Base Ten Blocks

• Number strips give a length model or number line representation for decimals.

• Base Ten Blocks provide an area model.

• A flat represents one whole, the long can represent tenths, and the units can represent hundredths

Base Ten Blocks

Model

Using base ten blocks model:

1.5 + 2.44

Do the same for:

2.8 + 0.63

How do these two problems differ?

What does regrouping mean?

If time permits…..

NCTM Technology Standard

www.nctm.org/families

www.visualfractions.com

• Technology is essential in teaching and learning mathematics; it influences the mathematics that is taught and enhances participant learning.

ClosureReflect on the following:

•Something I Learned

•Something I Wonder

•Something I Want to Share with My Family

Homework:

•Bringing Mathematics Home 5

•Decimal Problems I