Cogito
Grade 3 Math · Chapter 4 · Lesson 1
What Area Is
How much space a shape covers.
10 problems · about 12 minutes · 3.MD.C.5, 3.MD.C.6
What this lesson teaches
The child recognizes area as the amount of surface a shape covers, measured in unit squares.
- Area is how much space a shape covers.
- It is measured by counting equal squares.
- The squares must fit with no gaps and no overlaps.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Two-Step Problems With a Letter: 8 × 5 − 14 = ?
Answer 26
Why 8 × 5 = 40, and 40 − 14 = 26.
Review — Multiplication and Division Fluency: 7 × 6 = ?
Answer 42
Why 7 × 6 = 42.
Review — Patterns in the Times Tables: Is 8 × 7 odd or even?
Answer Even
Why An even factor makes the product even.
Warm Up
Straightforward practice. Get the method working first.
3 problemsA rectangle 7 across and 3 down. What is its area?
Answer 21
Why The area is 21 square units.
What does area measure?
Answer How much space a shape covers.
Why Area is the covering. The edge is something else.
A rectangle 4 across and 3 down. What is its area?
Answer 12
Why Count the squares.
Build It Up
The same ideas with more to keep track of.
1 problemA rectangle 6 across and 2 down. What is its area?
Answer 12
Why Two rows of 6.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsA rectangle 5 across and 5 down. What is its area?
Answer 25
Why Five rows of 5.
The Patio: A patio is covered by 24 square slabs. What is its area?
Answer 24 square units
Why The area is 24 square units.
The Rule: Can the squares overlap when you measure area?
Answer No. They must fit exactly.
Why Overlapping squares would count some space twice.