Cogito
Grade 2 Math · Chapter 8 · Lesson 8
Equal Shares, Different Shapes
Two halves of a shape need not look the same.
10 problems · about 13 minutes · 2.G.A.3
Figures — use these to answer the problems
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsFrom “Fourths”
How many fourths make one whole?
AnswerFrom “Thirds”
How many thirds make one whole?
AnswerFrom “Halves”
How many halves make one whole?
Answer
Warm Up
Straightforward practice. Get the method working first.
3 problemsTwo halves of a square are triangles. Is that allowed?
- Yes, if they are the same size.
- No. Halves are always rectangles.
What has to be equal about equal shares?
- How much they cover.
- What shape they are.
Must two halves be the same shape?
- No. Only the same size.
- Yes. Always.
Build It Up
The same ideas with more to keep track of.
1 problemMust two halves be the same size?
- Yes. That is what equal means.
- No. Roughly is fine.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsHow many different ways can a square be halved?
AnswerTwo Cuts
A square is cut corner to corner into two triangles. Are they halves?
- Yes. Both pieces are the same size.
- No. Halves must be rectangles.
Not Fair
A rectangle is cut into a big piece and a small piece. Are they halves?
- No. They are not the same size.
- Yes. There are two pieces.