Cogito
Grade 6 Math · Chapter 7 · Lesson 5
Breaking a Shape Apart
An awkward outline is a few easy ones.
10 problems · about 19 minutes · 6.G.A.1
Figure — use these to answer the problems
Area · squares inside
18
Perimeter · walk around
18
6 × 3 = 18 · 6 + 3 + 6 + 3 = 18
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsFrom “Area of a Trapezoid”
Parallel sides 5 and 11, height 4. Area?
AnswerFrom “Area of a Parallelogram”
Base 8, height 7. Area?
AnswerFrom “Surface Area from Nets”
A cube with edge 5. Surface area?
Answer
Warm Up
Straightforward practice. Get the method working first.
3 problemsA 7 by 4 rectangle with a 3 by 2 piece removed. Area left?
AnswerPieces of 3 by 3 and 4 by 2. Total area?
AnswerA 6 by 6 square with a 2 by 2 corner removed. Area left?
Answer
Build It Up
The same ideas with more to keep track of.
2 problemsPieces of 5 by 4 and a triangle of base 4, height 3. Total area?
AnswerMust the pieces overlap to cover the shape?
- No. Overlaps would be counted twice.
- Yes.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsTwo Rectangles
One piece is 4 by 3, the other 5 by 2. What is the total area?
AnswerThe Bite
A 10 by 5 rectangle with a 4 by 2 piece removed. What area is left?
Answer