Name_________________________________________________________
CCSS
8.NS.2
Date __________
Australian Football
An Australian football field is oval-shaped. Two fields are shown.
The perimeter P of each field can be approximated using the formula
P ≈ 2π
Field 1
b = 70 m
a 2 + b2
.
2
Field 2
b = 75 m
a = 90 m
a = 85 m
1. Write and simplify an expression for the perimeter of each field. Write
your answers in terms of π.
2. Without using a calculator, estimate the perimeter of each field to the
nearest tenth. Which field has the greater perimeter? Use 3.14 for π.
Use a calculator to check your estimations.
3. You are using a machine to paint the line that marks the perimeter of
Field 1. You paint 4 feet per second. About how many minutes will
it take?
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All rights reserved.
Big Ideas Math
Performance Tasks
3
CCSS
8.NS.2
8.NS.2
Common Core State Standard
Use rational approximations of irrational numbers to compare the size
of irrational numbers, locate them approximately on a number line
diagram, and estimate the value of expressions (e.g., π 2 ).
CCSS
8.NS.2
Grading Rubric
Answers
1. Field 1: 20π
Score
65 m; Field 2: 10π
257 m
2. Field 1: 508.7 m; Field 2: 502.4 m; Field 1 has the greater
perimeter.
3. about 7 minutes
2
3
1
Precision
1. Student understands how to simplify square root expressions.
2. Student understands how to compare irrational numbers and can
estimate the values of expressions involving irrational numbers.
3. Student uses understanding of rates to solve the problem.
Total Points
4
Big Ideas Math
Performance Tasks
1
2
1
10
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All rights reserved.