Transcript Presentation

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 Concepts
Define each term:
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•
•
•
Decade
Decimeter
Decagon
Decathlon
-- 10 years
-- One-tenth of a meter
-- A ten-sided shape
-- An Olympic event
consisting of 10
contests
What 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
At your tables…
• 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?
Which is Larger?
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•
•
•
•
•
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
Use the base ten
blocks to represent
the following decimal
values:
Can you represent
• 1.4
the numbers in more
• 0.65
than one way???
• 2.31
• 3.20
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…..
2.51 + 2.14
3.33 – 2.79
1.78 + 0.53
4.2 – 4.15
2.67 - 0.53
1.96 - 0.99
3.33 – 1.11
Make up your own!
NCTM Technology Standard
• Technology is essential in teaching and
learning mathematics; it influences the
mathematics that is taught and
enhances participant learning.
www.nctm.org/families
www.visualfractions.com
Closure
Reflect 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