Math · Geometry Lab

Area and Perimeter

Measuring shapes two ways: perimeter is the distance all the way around the edge, and area is how much flat space fits inside.
📐Two Ways to Measure a Shape
🚧PERIMETER
8 ft 8 ft 5 ft 5 ft
What it isThe total distance AROUND the outside edge.
Add up the sides8 + 5 + 8 + 5 = 26 ft
🚧 Like a fence or border
🟩AREA
fill it up! 8 units 5 units
What it isThe flat space INSIDE, in square units.
Multiply the sides8 × 5 = 40 sq units
🟩 Like a rug or grass
🧮Worked Example: The Backyard
🌱 length = 8 ft width = 5 ft
🏡 Fence + grass for an 8 ft × 5 ft yard
1Perimeter (fence): add all 4 sides
8 + 5 + 8 + 5 = 26 ft
2Area (grass): length × width
A = l × w = 8 × 5 = 40 sq ft
Buy 26 ft of fence and grass seed for 40 sq ft.
🔢Why Area Uses "Square Units"
1234 5678 9101112 1 square unit 4 units long 3 units wide Count them all: 4 × 3 = 12 = 12 square units of area
🔑Key Terms
🚧Perimeter The total distance AROUND the outside of a 2D shape.
🟩Area The space INSIDE a 2D shape, measured in square units.
Square Unit A 1-by-1 unit square used to measure area.
🔷Polygon A closed 2D shape made of straight line segments.
Rectangle A 4-sided polygon with 4 right angles.
📝Formula A math rule written with symbols, like A = l × w.
Remember: Perimeter is the FENCE around the edge (add the sides); Area is the RUG inside (length × width)!
✏️ Math Anchor Chart · Area and Perimeter
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