Cogito
Grade 1 Math · Chapter 4 · Lesson 3
Saying It the Ten Way
Thirteen is really "ten three".
10 problems · about 10 minutes · 1.NBT.B.2.b
What this lesson teaches
The child names teen numbers in the say-ten way as well as the usual way, which guards against digit reversal.
- Teen names hide the ten.
- Saying "ten four" shows it clearly.
- Both names mean the same number.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
5 problemsReview — 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.
Review — Subtracting From Ten: 10 − 6 = ?
Answer 4
Why 10 − 6 = 4.
Review — Taking Nothing and Taking All: 10 − 10 = ?
Answer 0
Why Take all away and none are left.
Warm Up
Straightforward practice. Get the method working first.
3 problemsTen five is which number?
Answer 15
Why Ten five is fifteen.
How many tens are in 17?
Answer 1
Why 17 is one ten and 7 ones.
Ten two is which number?
Answer 12
Why Ten and two.
Build It Up
The same ideas with more to keep track of.
1 problemTen eight is which number?
Answer 18
Why Ten and eight.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
1 problemSaying It Out Loud: One ten and 6 ones. What number is that?
Answer 16
Why Ten six is sixteen, written 16.