Download Perimeter of Geometric Figures

Name_________________________________________________________
CCSS
6.EE.4
Date __________
Perimeter of Geometric Figures
Use the rectangle and octagon below.
4x cm
1.5x cm
1.5x cm
1.5x cm
2x cm
1.5x cm
1.5x cm
1.5x cm
1.5x cm
1.5x cm
1. Write an expression for the perimeter of each figure.
2. Complete the table. What do you notice?
x
Perimeter of
rectangle
Perimeter of
octagon
1
2
3
4
5
6
7
8
3. What can you say about the expressions in Exercise 1?
4. What numbers could you fill in for the
side lengths of the triangle so that it has
the same perimeter as the rectangle and
octagon for every value of x?
____x cm
____x cm
____x cm
Copyright © Big Ideas Learning, LLC
All rights reserved.
Big Ideas Math
Performance Tasks
7
CCSS
6.EE.4
Common Core State Standard
6.EE.4 Identify when two expressions are equivalent (i.e., when the two expressions
name the same number regardless of which value is substituted into them).
CCSS
6.EE.4
Grading Rubric
Answers
Score
1. Rectangle: 4 x + 2 x + 4 x + 2 x or 12 x
Octagon: 1.5 x + 1.5 x + 1.5 x + 1.5 x + 1.5 x + 1.5 x + 1.5 x + 1.5 x
2
or 12 x
2.
x
Perimeter of
rectangle
Perimeter of
octagon
1
12
12
2
24
24
3
36
36
4
48
48
5
60
60
6
72
72
7
84
84
8
96
96
2
No matter what the value of x is, the perimeter of the rectangle and
the perimeter of the octagon are equal.
3. They are equivalent.
1
4. Sample answer: Sides lengths are 3x, 4x, and 5x.
1
Precision
1. Student shows understanding of how to write an expression for the
perimeter of a figure.
2
2. Student shows understanding of how to evaluate expressions at
specific values of their variables, and can recognize a pattern from
the table.
3. Student identifies when two expressions are equivalent.
1
4. Student uses reasoning to find another equivalent expression.
1
Total Points
8
2
Big Ideas Math
Performance Tasks
12
Copyright © Big Ideas Learning, LLC
All rights reserved.