Transcript What is a decimal?

January 6, 2014
“Life is not so much about beginnings and
endings as it is about going on and on and on. It
is about muddling through the middle.”
Anna Quindlen
POTD
After a class party 3¼ cartons of orange juice
and 2¾ cartons of apple juice remained from the
10 cartons the teacher purchased. How much
juice was used?
Write 2
A.
4
5
B.
7
5
C.
12
5
D.
2
7
2
as an improper fraction.
5
28
9
Write
A.
3
9
1
9
B. 3
C.
D. 3
9
3
3
9
as a mixed number.
What does dec- mean?
What words contain the prefix dec-?
What is a decimal?
A decimal is a part of a whole.
Think about money.
One dollar, 4 dimes, and 3 pennies is
written in decimal form.
$1.43
It takes 10 dimes to make 1 dollar, so a
dime is one-tenth of a dollar.
One dollar is equal to 10 dimes.
It takes 100 pennies to make a
dollar, so each penny is equal to
one-hundredth of a dollar.
One dime is equal to 10 pennies.
It takes 10 dimes to make 1 dollar, so a
dime is one-tenth of a dollar.
$0.10 = one dime
It takes 100 pennies to make 1 dollar, so
a penny is one-hundredth of a dollar.
$0.01 = one penny
Practice writing these amounts of money as
decimals on a sheet of paper.
71 cents
6 cents
119 cents
215 cents
What are decimals?
Decimals are numbers that include
fractional parts using denominators
that are powers of ten. As we move to
the right of the decimal, every
number place is 10 times smaller
ten-thousandths
thousandths
hundredths
tenths
ones
tens
hundreds
thousands
Everything to the left of Everything to the right
of the decimal point is
the decimal point is a
PART of a whole.
WHOLE number.
What is a decimal point?
A decimal point is to the right of
the ones place.
Where is the tenths place?
The tenths place is to the right
of the decimal point.
Where is the hundredths place?
The hundredths place is to the
right of the tenths place.
Decimal Place Value Chart
Thirty-two out
of one hundred
are shaded
0.32
thirty-two
hundredths
32
100
eighty out of
one hundred
are shaded
0.80
eighty
hundredths
80
100
Reading Decimals
•
•
•
•
Say what you see before the decimal
Say “and” for the decimal
Say what you see after the decimal
Say the place value of the final digit
• To write in words, you write what you say
five hundred eighty
and
.
580 324
three hundred twenty-four thousandths
One
and
forty-six hundredths
three and forty
seven tenths
three and forty
seven hundredths
Three and forty
seven thousandths
Three and forty
seven hundred
seventeen
and
eighty-two tenths
seventeen
thousand eighty
two
seventeen
and
eighty-two
hundredths
seventeen
and
eighty-two
thousandths
Additional Information
•1 think of ½ of a dollar… $0.50
2
•1 think of splitting a dollar in fourths
4
•1 think of 1/5 of 100
5
January 7, 2014
“Isn't it nice to think that tomorrow is a
new day with no mistakes in it yet?”
― L.M. Montgomery
POTD
Lia read her new book for 2¾ of an hour on
Tuesday. If she read for 1¼ of an hour before
lunch, how long did she read for after lunch?
Write 3
A.
B.
31
8
7
11
C.
10
8
D.
24
8
7
as an improper fraction.
8
Write
A. 5
2
6
B. 4
3
2
C. 6
D. 5
34
as a mixed number.
6
1
3
2
3
Homework Review
Comparing Decimals
Using Models
• If you are comparing tenths to hundredths, you
can use a tenths grid and a hundredths grid.
Here, you can see that 0.4 is greater than 0.36.
The Easy Way
• Line up the numbers vertically by the decimal
point.
• Add “0” to fill in any missing spaces.
• Compare from left to right.
EX: Compare 43.2 and 43.198
Half pipe Results
Sara
42.1
Danny
42.5
Ross
42.0
Bethany 40.7
Jacob
46.1
•
Compare Sara’s score with
Danny’s score.
1.
Line Up Decimal Points
– Sara: 42.1
– Danny: 42.5
2.
Start at the left and find the first
place where the digits differ.
Compare the digits
– 1<5
– 42.1<42.5
– This means Sara’s score was lower
than Danny’s score.
Equivalent Decimals
• Decimals that name the same number are
called equivalent decimals.
• 0.60 and 0.6
• Are these the same???
0.60
=
0.6
Decimal Cards
Each partner will shade their card.
January 8, 2014
A journey of a thousand miles begins with a
single step.”
– Lao Tzu
POTD
15 friends want to order pizza for dinner. They
predict that each person will eat 1/3 of a pizza.
How many pizzas should they order?
Write as an improper fraction and mixed
number.
Write 5
A.
B.
50
10
6
10
C.
51
15
D.
51
10
1
as an improper fraction.
10
Write
A. 4
3
5
B. 5
1
5
C. 4
D. 4
23
as a mixed number.
5
2
5
3
4
Homework
Review
To add decimals
• Line up the decimal points and add the
columns from right to left.
• Place a decimal point in the answer directly
below the other decimal points.
Example 1
0.64 + 0.39
Line up the decimal points.
0.64
+ 0.39
__________________________
Add the columns.
0.64
+ 0.39
__________________________
1.03
Adding
Examples:
4.55 + 11.3
Put the first number on the top
of the second number and line
up the decimals.
4.55
+ 11.3 0
15.85
You can add
a zero to
help keep
everything
lined up
When adding or
subtracting you
always start from
the right and
work left.
6.44 + 16
When there is
not a decimal
put one
behind the
number.
Line up the
decimal
6.44
+ 16. 0
22.44
Add a zero
to line up
everything
Adding to 1
Adding to 1 Continued
January 9, 2014
“There will come a time when you believe
everything is finished. That will be the beginning.”
– Louis L’Amour
POTD
Tom picked 10 plums from a tree in the garden
and ate 3/5 of them before lunch. How many
plums did he have left?
Homework
Review
Runner’s Log
Venetta and her mother get exercise every morning
by going for a walk together. Instead of walking the
same amount every day, they decide to have a goal
of walking a total of 2 miles every week. In order to
keep track they keep a log that looks like this:
Monday- 0.5 mile
Tuesday- 0.6 mile
What fraction did they walk on Monday? (simplify)
What fraction did they walk on Tuesday? (simplify)
Did they walk more or less on Tuesday than
Monday? Estimate the total distance they walked
in those 2 days.
SAB Unit 6 page 52
SAB Unit 6 page 53
January 10, 2014
“Take the first step in faith. You don’t have to
see the whole staircase, just take the first step.”
– Martin Luther King
POTD
A farmer owns 4 acres of farmland. He grows
potatoes on 3/8 of the land. On how many acres
of land does the farmer grow potatoes?
Homework
Review ODD
Decimal Quiz
Review
• Word, standard, model form
• Comparing decimals
• Writing decimals as fractions
• Adding fractions
SAB Unit 6 pages 57-58