Cogito
Grade 2 Math · Chapter 1 · Lesson 2
Near Doubles
If you know a double, you know its neighbours.
10 problems · about 12 minutes · 2.OA.B.2
What this lesson teaches
The child solves near-double facts such as 7 + 8 by recalling the double and adjusting by one.
- A near double sits one away from a double.
- Recall the double, then add or take away one.
- Using a fact you know beats counting every time.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Doubles: 7 + 7 = ?
Answer 14
Why 7 + 7 = 14.
Review — Doubles: Which of these is a double?
Answer 9 + 9
Why Only 9 + 9 has two equal parts.
Warm Up
Straightforward practice. Get the method working first.
4 problems8 + 9 = ?
Answer 17
Why 8 + 8 = 16, and one more makes 17.
You know 6 + 6 = 12. What is 6 + 7?
Answer 13
Why One more than 12 is 13.
4 + 5 = ?
Answer 9
Why 4 + 4 is 8.
7 + 8 = ?
Answer 15
Why 7 + 7 is 14.
Build It Up
The same ideas with more to keep track of.
2 problems9 + 8 = ?
Answer 17
Why 8 + 8 is 16.
6 + 5 = ?
Answer 11
Why 5 + 5 is 10.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsTwo Boxes: One box holds 8 pencils. The other holds 9. How many pencils in all?
Answer 17 pencils
Why 8 + 8 = 16, and one more makes 17.
Football Teams: One team has 5 players. The other has 6. How many players are on the field?
Answer 11 players
Why 5 + 5 = 10, and one more makes 11.