Study guide: Distinguish Area from Perimeter
Count unit squares, add non-overlapping areas, and calculate boundaries and missing sides.
Ideas to explain in your own words
- Area counts how many same-size unit squares cover a region without gaps or overlap.
- A composite region can be split into rectangles whose interiors do not overlap.
- Perimeter is the distance all the way around a figure.
- A supplied polygon perimeter is the sum of all its boundary sides.
Useful vocabulary
- area
- The amount of flat region covered, measured in square units.
- perimeter
- The length around the outside boundary.
Watch your reasoning
- Report square units rather than ordinary length units.
- Do not add overlapped areas without correcting the double count.
- A rectangle has two sides of each given dimension.
- Do not assume opposite sides match unless a shape definition supplies that fact.
A worked review example
A rectangle five units long and four units wide holds four rows of five unit squares. Its area is 5×4=20 square units. Twenty measures the region inside, not the length of its edge. A full grid shows all twenty squares without gaps. Area answers how much region is covered. Report square units rather than ordinary length units. Tile the region with an equal-square grid before applying the product.
Make a practice plan
- Find Rectangular Area with Unit Squares: A 7 by 6 rectangle has area 42 square units.
- Add Areas of Non-Overlapping Parts: Parts 4×6 and 3×2 with no overlap have total area 30 square units.
- Find Rectangle Perimeter: A 9 cm by 4 cm rectangle has perimeter 26 cm.
- Find a Missing Side from a Perimeter: Perimeter 35 cm with other sides 9,8,7 cm gives missing side 11 cm.