Cogito
Grade 1 Math · Chapter 3 · Lesson 5
What Changed?
You know the start and the end. What happened in between?
10 problems · about 12 minutes · 1.OA.A.1, 1.OA.B.4
What this lesson teaches
The child solves take-from-with-change-unknown stories.
- Sometimes the missing bit is what changed.
- You know the start and the end.
- Count up from the end to the start.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
5 problemsReview — The Hidden Part: Whole 9, one part 4. What is the other part?
Answer 5
Why 4 + 5 = 9.
Review — Taking Away: 7 − 3 = ?
Answer 4
Why 7 − 3 = 4.
Review — Counting Up To Subtract: 9 − 7 = ?
Answer 2
Why Two hops, so the answer is 2.
Review — How Many More To Make It?: 3 + ? = 7
Answer 4
Why 3 + 4 = 7.
Review — Facts to Ten: 7 + 3 = ?
Answer 10
Why 7 + 3 = 10.
Warm Up
Straightforward practice. Get the method working first.
3 problems9 − ? = 6
Answer 3
Why 9 − 3 = 6.
7 − ? = 2
Answer 5
Why 7 − 5 = 2.
8 − ? = 5
Answer 3
Why Count up from 5 to 8.
Build It Up
The same ideas with more to keep track of.
1 problem10 − ? = 6
Answer 4
Why Count up from 6 to 10.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
1 problemThe Bird Table: There were 7 birds. Now there are 3. How many flew away?
Answer 4 birds
Why 7 − 4 = 3, so 4 flew away.