Problem 5 worked answer
Fence the Wheat Farm
Designed for Grade 3 · Uses Middle Grade 3 math · About 2–6 minutes
At a glance
- Part 1: The farm contains 40 square blocks of ground.
- Part 2: The full perimeter is 26 blocks. After the 2-block gate opening, Sam must fence 24 blocks, so the 24 fence blocks are exactly enough.
1. Find the area
Area measures the ground inside the rectangle. Multiply its length by its width:
.
The farm has an area of 40 square blocks. The unit is square blocks because the area counts two-dimensional units covering the inside.
2. Find the fence needed
Perimeter measures the distance around all four sides. The rectangle has two 8-block sides and two 5-block sides:
.
So the full perimeter is 26 blocks. Sam leaves a 2-block section open for the gate:
.
Sam must fence 24 blocks of the edge. Because he has 24 fence blocks, he has exactly enough.
Check
The perimeter can also be grouped as . Putting the fence and gate portions back together gives , the full edge.
Technical fit and rating
Geometry · Measurement · Number and operations
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