Transcript PROBLEM SOLVING

Thursday, November 4
Today’s Agenda
1.
2.
No homework due today
Fill in planner
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3.
Bell Work
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5
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12
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 
4 3 2
Today’s assignment is
Practice 5-6
Chapter 5 test will be
Monday
3 2 1
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4 3 12
3 2
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 1
4 3
8
4. Note Taking:
Working backwards
to solve a problem
5. Review operations
with fractions
6. Fraction Jeopardy
Today’s Objective
SWBAT
 solve problems by working
backwards
Why?
 To solve real world
problems involving time and
money
Why work backwards?
Working backwards from information you already
know will sometimes help you solve a problem.
Problem 1
 You are planning to go to a baseball game
that starts at 1:00 pm. You want to arrive
half an hour early. Your walk to the train
station is about 10 minutes long. The train
ride to the city takes ¾ of an hour. After
you arrive in the city, you will need to walk
for about 10 more minutes to get to the
stadium. What time should you plan to
leave?
Understand the problem
1. What do you want to find?
What time you should leave home
2. What is your arrival time?
12:30 pm
3. How much time will you spend walking to
10 minutes
the train?
4. How much time will you spend on the
train? ¾ hour
5. How much time will you spend walking
from the train?
10 minutes
Let’s Work backwards
The game starts at 1:00
Subtract 30 minutes
(because we want to
arrive early)
Subtract 10 minutes we
will spend walking to the
stadium
Let’s Work Backwards
Subtract ¾ of an hour
that we will spend on the
train
Let’s Work Backwards
Subtract the 10 minutes
we will spend walking to
the train
Let’s Work Backwards
We should leave the
house at 11:25
Your turn to try a couple…
 Make sure you…
– Show that you pulled the important information
from the problem (3 pts)
– Show your working backwards steps (4 pts)
– Circle your answer (2 pts)
Each problem is worth…9 pts!
Adding Fractions (Review)
1 5
2 
3 7
Do I have to get rid of the mixed
number first?
Adding Fractions (Review)
1 5
2 
3 7
What is the LCD of my fractions?
Hmmm… let me start listing
multiplies of 7…
7, 14, 21, 28, …
Adding Fractions (Review)
1 5
7 15
2  2 
3 7
21 21
Okay, I changed my fractions so
that I have a common denominator,
now what?!?
Adding Fractions (Review)
7 15
22
2  2
21 21
21
Okay, I add the numerators and
keep the denominators the same.
Now, I have, a mixed number with
an improper fraction?!? That can’t
be right…
Adding Fractions (Review)
1
1
2 1  3
21
21
Oh, I know I have to separate the
improper fraction into a mixed
number and add it to the whole
number I already had…
Adding Fractions (Review)
1 5
1
2  3
3 7
21
Cool, thanks for your help!
Subtracting Fractions (Review)
5
1
1 3
9
3
Yikes, I am taking away more than I
started with… I think making these
into improper fractions first will
make it less confusing.
Subtracting Fractions (Review)
5
1 14 10
1 3  
9
3 9 3
There…I feel better already.
How about an LCD. Hmmm, what
should I use???
Subtracting Fractions (Review)
14 30

9
9
Cool, I only had to change one of my
fractions!
What the heck is 14-30 anyway?
Subtracting Fractions (Review)
14 30
16


9 9
9
I knew my answer was going to be
negative, since I was taking away
more than I started with.
Now I just need to make it a mixed
number and I am done!
Subtracting Fractions (Review)
16
7
  1
9
9
When I change it to a mixed
number, I get to ignore the
negative sign! (I like that)
Multiplying Fractions (Review)
1
1
 2
9
3
Woot Woot…multiplying fractions is
so much easier than adding and
subtracting.
No more LCD’s…whoopee!!!!
Multiplying Fractions (Review)
1 7
 
9 3
I just make any mixed numbers or
whole numbers fractions first,
right?
Can I pull any factors from the
numerator or denominator?
Multiplying Fractions (Review)
1 7
7
  
9 3
27
My answer is negative because a
negative times a positive always
is…duh.
Dividing Fractions (Review)
1
2
 (2 )
9
3
Okay, dividing fractions is just a
teeny bit trickier. We can do it,
right?
Help me out…what do I do first?
Dividing Fractions (Review)
1
2 1
8
 (2 )   ( )
9
3 9
3
Oh you’re right, I always have to
convert any mixed numbers or whole
numbers to fractions first. How did
you get so smart?
Ugg..now what. I change it to
multiplying by…what was that “r” word
again?
Dividing Fractions (Review)
1
8 1
3
 ( )   ( )
9
3 9
8
Oh yeah, RECIPROCAL. Dividing is the
same things as multiplying by the
RECIPROCAL. I get it.
I like cancelling…can I do any
cancelling?
Dividing Fractions (Review)
1
1
3
 ( )
9
8
3
Oh yeah, RECIPROCAL. Dividing is the
same things as multiplying by the
RECIPROCAL. I get it.
I like cancelling…can I do any
cancelling?
Dividing Fractions (Review)
1
1
3
1
 ( )  
9
8
24
3
We got it! Thanks for your help!
Let’s play Jeopardy
 What are our expectations?






B1
B3
B4
G1
G3
G4
LCM Review
 How do I find the LCM of 6a2 and 18a3
Compare and order fractions
 Order -1, -1/2, 3/4, and 2/5 from least to
greatest
How do I go from a fraction to a
decimal?
5
8
How about from a decimal to a
fraction?
 0.54
 0.777… or
0.7
More Jeopardy?
 B1
 B3
 B4
 G1
 G3
 G4