21st Century Lessons
Evaluating Expression
Primary Lesson Designers:
Kristie Conners
Sean Moran
1
Warm Up
OBJECTIVE: SWBAT evaluate algebraic expressions.
Language Objective: SWBAT describe the steps to evaluating expressions.
A magic store is selling exploding pens for
$3 each plus $1 for tax.
Kyle thinks you can figure out the cost of 10
pens with the
below.
3 10 1
Do you agree or disagree?
Explain.
Click to reveal next part
Agenda
7
Agenda:
OBJECTIVE: SWBAT evaluate algebraic expressions.
Language Objective: SWBAT describe the steps to evaluating expressions.
1) Warm Up
2) Launch
Individual
Shopping with Marvin- Whole Class/Pairs
3) Explore- 1
Evaluating with Marvin- Whole Class
4) Explore- 2
Practice with Formulas- Whole Class
Class work: Can’t Wait to Evaluate – Groups
5) Practice
6) Assessment Exit Slip- Individual
8
Launch- Shopping with Marvin
Marvin the Math Magician has a problem for you.
He wants to buy some magic wands
and some magician hats.
The wands cost $8 each and $5
for each hat.
How much will Marvin have to
pay for 12 wands and 7 hats?
Agenda
9
Launch- Shopping with Marvin
How did you get your answer?
The wands cost $8 each and $5 for each hat.
How much will Marvin have to pay for 12 wands and 7 hats?
How can we write a
to show our answer of 131?
8 12  5 7
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Agenda
10
Explore 1- Evaluating with Marvin
How much will Marvin have to pay
for 6 wands and 3 hats?
Write an numerical expression to
find the answer.
Remember: the wands cost $8 each and $5 for each hat.
8 6  5 3
48 15
63
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Agenda
11
Explore 1- Evaluating with Marvin
812 5 7
8 6 5 3
12 wands
7 hats
The wands cost $8
each and $5 for each
hat.
6 wands
3 hats
What changed in the two examples?
Sometimes it helps to represent a problem as
an


w= # of wands
h= # of hats
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Agenda
12
Explore 1- Evaluating with Marvin
How much will Marvin have to pay
for 10 wands and 2 hats? w = 10 h = 2

 
8w  5h
w 5 h
810
2
80 10
90
This is called
substitution!!
We just
evaluated the
expression.
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13
evaluate
Agenda
Explore 1- Evaluating with Marvin
Find the cost of buying 9 wands and 7 hats.
w= 9
h= 7

15
Steps:
1. Copy the expression.
8w  5h
the value
h 2.in Substitute
9 5 7
8w
for the variable.
72 35 3. Evaluate using the
107 order of operations.
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Agenda
Explore 2- Formulas
Flashback…
Objective: evaluate algebraic expressions.
We can use the process of evaluating to solve problems in the real
world.
For example: engineers, architects and builders use geometric
formulas every day.
Circumference
C  d
Volume
Rectangular Prism

V  lwh
Surface Area
Cylinder
SA  2r  dh
2
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Agenda
16
Explore 2- Formulas
Volume is the amount of space a shape takes
up. The expression for calculating the
volume of the rectangular
prism is below.
5ft
lwh
l
w
h
Find the volume
l w h
or
Steps:
1. Copy the expression.
36 5
3
180 ft
2. Substitute the value
in for the variable.
3. Evaluate using the
order of operations.
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Agenda
17
Explore 2- Formulas
Surface Area is the total of the area of all
sides. The expression for calculating the
surface area of a rectangular
prism is below.
2lw 2lh 2wh
Find the volume.
2lw  2lh 2wh
2  2  2 
72  90  40
2
202 ft



18




5ft
Steps:
1. Copy the expression.
2. Substitute the value
in for the variable.
3. Evaluate using the
order of operations.
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Agenda
Practice- Class work
Can’t Wait To Evaluate!
Directions: Each group receives a set of Evaluation Cards along with two different colored
number cubes. Before starting, the team decides which color cube stands for which variable.
(Example: the red cube replaces a, the green cube replaces b.) One person in the group rolls
the number cubes. Students use the numbers to evaluate the expression.
a=____
a b
3a 2b
2(ab)
ab
a b
3(a  b)
2
3a 1
2
2b  5
b 
a  a 
19
b=____

a  4b
ab 

ab

Agenda
Summary
Can’t Wait To Evaluate!
Click each problem for demonstration
a=____
a b
3a 2b
2(ab)
ab
a b
3(a  b)
2
3a 1
2
2b  5
b 
a  a 
20
b=____

a  4b
ab 

ab

Agenda
Exit Slip
Kiara was asked to evaluate the
expression 27  p . Her answer was 14.
Did she substitute 11, 13, or 15?
How do you know?

Answer : 13
27 – 13
14
Agenda
32