Cogito
Grade 1 Math · Chapter 8 · Lesson 5
Making the Next Ten
Use the make-ten move on bigger numbers.
10 problems · about 13 minutes · 1.NBT.C.4, 1.OA.C.6
What this lesson teaches
The child adds a one-digit number to a two-digit number by first making the next ten, as in 28 + 5 = 28 + 2 + 3.
- Get to the next ten first.
- Split the second number to do it.
- 28 + 5 is 30 + 3, which is 33.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
4 problemsReview — Adding Ones Without Making a New Ten: 31 + 6 = ?
Answer 37
Why 1 one and 6 ones is 7 ones.
Review — Adding Tens to Any Number: 16 + 20 = ?
Answer 36
Why 1 ten and 2 tens is 3 tens, with 6 ones.
Review — Subtracting Tens From Tens: 30 − 20 = ?
Answer 10
Why One ten is left, which is 10.
Review — Adding Tens to Tens: 20 + 10 = ?
Answer 30
Why 2 tens and 1 ten is 3 tens.
Warm Up
Straightforward practice. Get the method working first.
3 problems29 + 5 = ?
Answer 34
Why 30 and 4 more is 34.
What does 27 need to reach 30?
Answer 3
Why 27 and 3 makes 30.
18 + 5 = ?
Answer 23
Why 18 needs 2 to reach 20.
Build It Up
The same ideas with more to keep track of.
1 problem27 + 6 = ?
Answer 33
Why 27 needs 3 to reach 30.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problems26 + 8 = ?
Answer 34
Why 26 needs 4 to reach 30.
Beads: Leo has 29 beads. He adds 4 more. How many now?
Answer 33 beads
Why 29 + 1 + 3 = 33.