Cogito
Grade 1 Math · Chapter 4 · Lesson 4
Writing Teen Numbers
The tens digit always comes first.
10 problems · about 11 minutes · 1.NBT.B.2, 1.NBT.A.1
What this lesson teaches
The child reads and writes numerals 11 to 20 and matches them to quantities.
- The first digit is the tens.
- The second digit is the ones.
- 13 and 31 are different numbers.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
4 problemsReview — Saying It the Ten Way: Ten five is which number?
Answer 15
Why Ten five is fifteen.
Review — Ten and Some More: 10 + 2 = ?
Answer 12
Why 10 + 2 = 12.
Review — Ten Ones Make One Ten: How many ones are in one ten?
Answer 10
Why One ten is made of ten ones.
Review — Adding and Subtracting to Ten: 7 − 2 = ?
Answer 5
Why 7 − 2 = 5.
Warm Up
Straightforward practice. Get the method working first.
3 problemsIn 16, how many ones are there?
Answer 6
Why 16 is one ten and 6 ones.
One ten and 2 ones is which number?
Answer 12
Why That is 12.
One ten and 1 one is which number?
Answer 11
Why Ten one.
Build It Up
The same ideas with more to keep track of.
1 problemOne ten and 0 ones is which number?
Answer 10
Why Just the ten.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsTwo tens and 0 ones is which number?
Answer 20
Why Two full tens.
Writing It Down: One ten and 9 ones. What number do you write?
Answer 19
Why One ten and 9 ones is 19.