Activity III: Calculations from the Farm (Grade Level 712)
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Calculations from the Farm 
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Standards:
NCTM Standard 4* Measurement
NCTM Standard 9* Connections
* These standards have been adopted and are based on the information from Principals and Standards for School Mathematics: Discussion Draft, October 1998, National Council Teachers of Mathematics.
Calculations
from the Farm
How
big is an acre?
An old unit of measure
is the rod. A rod is 16 1/2 feet long. A square rod is a square plot
of ground 16 1/2 feet on a side. An acre is 160 square rods.
2. Calculate the
area of your classroom. How many classrooms would it take to make an
acre? (Answers will vary.)
3. A football field
is 160 feet wide and 100 yards from goal line to goal line. How does
this area compare to an acre?
4. If the acre field
was a square, what would its dimensions be?
5. If an acre field
was 1 rod (16 1/2 feet) wide how long would it be? What part of a mile
(5280 feet) is this length?
It is common these
days for farmers to have fields of 120 acres.
6. What are some
possible dimensions for a 120 acre field? (Answers will vary. This is
a good question for using a spreadsheet or calculator.)
7. If the 120 acre
field was square, what would its dimensions be?
When planting corn,
it is common for the rows to be 30 inches apart and the goal is to have
a corn stalk about every 4 inches.
8. Suppose you have
an acre of field and plant rows that are 30 inches apart. What is the
combined length of all the rows in the acre field?
9. If seeds are
planted every 4 inches, how many seeds are needed for an acre field?
How many seeds are needed to plant a 120 acre field?
(Answers will vary
as students may use the various foot measures they generated in problem
8.)
10. In the fall,
the farmer hopes to be able to harvest about 175 bushels per acre. A
bushel of corn weighs about 56 lb. How much would the corn from a 120
acre field weigh?
