Transcript Ratios

th
7
Grade Math
Week of 11/17/14
Information from :
Purple Math, Holt Rinehart Winston TB, Math-Aides
http://net.cmsdnet.net/schools/math/sld005.htm
http://www.mathsisfun.com/
https://www.sinclair.edu/centers/tlc/pub/handouts_worksheets/mathe
matics/DEV085/7_integers/085_signed_integer_word_problems.pdf
Monday: Bell Work
Write and solve the equation or inequality
In a class total of 65 students. 17 students failed the final
exams. Write a statement to the show the
number of students that passed?
Shana bought many dresses for her dances. She
has 12 bags of dresses. In each bag there were 5
dresses. She gave one bag to her sister. Write a
statement that determines the number of dresses
she has left.
Agenda
1- bell work
2- Agenda *HW- TB p. 266 1-10
3- vocabulary word of the day
4- Objective
5- lesson – Ratios/ Rates (add to NB)
6- exit ticket
21. Linear Equation
What does this
word mean to
you?
Examples…
This word actually
means…..
equation whose solutions
form a straight line when
graphed on a coordinate grid.
Explain how
you would use
this word in
math.
22. Quantity
What does this
word mean to
you?
This word actually
means…..
total value of a
given group or
specific amount.
Examples…
Explain how
you would use
this word in
math.
Lesson
7. RP.2. Recognize and represent
proportional relationships between
quantities.
Ratios
A ratio compares values.
A ratio says how much of one thing there is compared to another
thing.
There are 3 blue squares to 1 yellow
square
Ratios
A ratio compares values.
A ratio says how much of one thing there is compared to another
thing. ***must be same unit****
There are 3 blue squares to 1 yellow
square
Ratios can be shown in different ways:
Using the ":" to separate the values:
3:1
Instead of the ":" we can use the word "to":
3 to 1
Or write it like a fraction:
3
1
*do not write as a mixed number or whole #
A ratio can be scaled up:
Here the ratio is also 3 blue squares to 1
yellow square,even though there are more
squares.
Using Ratios
The trick with ratios is to always multiply or
divide the numbers by the same value.
Example:
4 : 5 is the same as 4×2 : 5×2 = 8 :
10
Recipes
Example: A Recipe for pancakes uses 3 cups of flour and 2
cups of milk.
So the ratio of flour to milk is 3 : 2
To make pancakes for a LOT of people we might need 4
times the quantity, so we multiply the numbers by 4:
3×4 : 2×4 = 12 : 8
In other words, 12 cups of flour and 8 cups of milk.
Try this!!
Types of Ratios
Part to Part: compare two parts in the
group
Example: 10 boys to 8 girls
Part to Whole: compare a part to a
whole
Example: 10 boys to 18 students
These ratios are shots made to shots taken
1) Are these part to part or part to whole?
2) Who is the best at freethrows?
3) List the ratios from least to greatest.
(answer the following)
Rates
A rate is a little bit different than the ratio,
it is a special ratio. It is a comparison of
measurements that have different units,
like cents and grams. A unit rate is a rate
with a denominator of 1.
Rate Examples
For example, if a 12-ounce can of corn costs
69¢, the rate is 69¢ for 12 ounces. The
first term of the ratio is measured in cents;
the second term in ounces. You can write
this rate as 69¢/12 ounces or 69¢:12
ounces. Both expressions mean that you
pay 69¢ "for every" 12 ounces of corn.
Lesson Review
Exit / Closure
• Partner discussion with neighbor (s)
What is the difference between a rate and a
ratio?
Tuesday: Bell Work *HW on desk
Write and solve the equation or inequality
A school library has 400 books. If 10 students
took a book to read, write a statement to find the
remaining books in library? Solve
Josephine estimated that he found 200 pennies.
He needs $5.00 to take the bus. How many more
pennies does he need to find?
Agenda
1- bell work
2- Agenda *WB p. 35-36
3- vocabulary word of the day
4- Objective
5- Check Homework
6- lesson *Writing/Identifying Proportions
(add to NB)
7- exit ticket
23. Coefficient
What does this
word mean to
you?
Examples…
This word actually
means…..
the number that is
multiplied by the
variable in an algebraic
expression/equation.
Explain how
you would use
this word in
math.
Lesson
7. RP.2. Recognize and represent
proportional relationships between
quantities.
Identifying/ Writing Proportions
Use what you know
About proportions to
Put these numbers
In order to create a
proportion
TB p. 224
Exit/ Closure
Discuss with your neighbor...
Would it be better to earn $272 in 40 hours
or $220 in 30 hours?
Why??
Wednesday: Bell Work
*HW on desk
Write and solve the equation or inequality
Jack works in departmental store. He needs to
sell $1,000 of merchandise. He has sold $400. He
sells $60 of merchandise a month. Find the number
of months Jack needs to complete the target?
Sara wants to her reduce weight. Her present
weight is 75 kg. She is determined to be 65 kg.
Every month she loses 2 kg weight. In how many
months will she lose 10 kg of weight?
Agenda
1- bell work
2- Agenda *in class problems- no homework
3- vocabulary word of the day
4- Objective
5- Check Homework
6- lesson *Solving for proportions
7- exit ticket
24. Variable
What does this
word mean to
you?
This word actually
means…..
a symbol used to
represent a quantity
that can change.
Examples…
Explain how
you would use
this word in
math.
Lesson
7. RP.2. Recognize and represent
proportional relationships between
quantities.
Solving proportions
If twelve inches correspond to 30.48 centimeters, how many centimeters are
there in thirty inches?
I will set up my ratios with "inches" on top, and will use "c" to stand for the
number of centimeters for which they've asked me.
inches:centimeters: 12
30.48
12 =
30.48
= 30
c
30
c
12c = (30)(30.48)
12c = 914.4
c = 76.2
Thirty inches corresponds to 76.2 cm.
Contextual Proportion Problems
Exit / Closure
Partner discussion with your neighbor (s)
What type of equation do you write when
solving proportions?
Thursday: Bell Work
Write and solve the equations or inequalities
500 students went on picnic trip. 10 students
travelled in each car. Find out how many cars were
used for the picnic trip?
John bought ten books all at the same price. The
total cost of the books was $242. He gave two
books to his friend. What was the value of the books
that he gave to his friend?
Agenda
1- bell work
2- Agenda *finish problems if needed
3- vocabulary word of the day
4- Objective
5- lesson *N2K and Unit Rate
6- exit ticket
25. Reciprocal
What does this
word mean to
you?
This word actually
means…..
one of two numbers
whose product is
one.
Examples…
Explain how
you would use
this word in
math.
Lesson
7.RP.1 Compute unit rates associated with
ratios of fractions, including ratios of
lengths, areas and other quantities measured
in like or different units. For example, if a
person walks 1/2 mile in each ¼ hour,
compute the unit rate as the complex fraction
1/2/1/4 miles per hour, equivalently 2 miles
per hour.
• N2K 2
Unit Rates
Video
Additional videos
1
2
Word Problems
Solve the word problems
Need to Know 2
CTSolve the problem and choose the most correct answer. JUSTIFY your
Answer in words!!!
CRLook at the work in the problem. Choose the answer that does not work
With the given problem. JUSTIFY in words as to why that answer does not
Can not be used with the problem.
Exit / Closure
• Partner discussion with your neighbor (s)
What skills were important for this need to know?
What were your strengths or weaknesses?