Area and perimeter

Practice 3 items →

Perimeter is a length; area is a count of unit squares; they do not move together. Students use the rectangle and square formulas, find a missing side from a known area or perimeter, and decompose composite rectilinear figures.

Specification · for a parent or teacher

Part no.: area-perimeter-rectilinear
Course: Advanced Math 4 · Unit 11
Realm: Shapes
Difficulty: 2 of 4 — Grade 4–5. Two steps, or one idea in a story.
Qty: 3 items

Part no. is the node's id; the realm is the kind of math; qty is how many practice items it carries.

Students can

$A = \ell w$ , $A = s^2$ ; find a missing side given $A$ or $P$ ; decompose composite rectilinear figures.

Ready when

a rectilinear “L” with three labeled sides, they find $A$ and $P$ without being given the other three.

Formulas

Rectangle area

A = \ell w

Rectangle perimeter

P = 2(\ell + w)

Square area

A = s^2

Watch for

doubling both $A$ and $P$ when both sides double; using the outer path as area.

Before · requires

Multiplicationmulti-digit-multiplication · Math 4

After · used by

Area of plane figuresarea-triangles-trapezoids · Math 6

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