Cogito
Kindergarten Math · Chapter 6 · Lesson 3
Comparing Teen Numbers
The extras decide.
10 problems · about 8 minutes · K.NBT.A.1, K.CC.C.7
What this lesson teaches
The child compares two teen numbers by comparing their extra ones.
- Every teen number has one ten, so the tens are equal.
- The extra ones decide which is bigger.
- More extras means a bigger number.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
4 problemsReview — Building Teen Numbers: 10 + 5 = ?
Answer 15
Why Fifteen.
Review — Ten and Some More: 18 is 10 and how many?
Answer 8
Why Eight.
Review — Sums That Make Ten: 3 + ? = 10
Answer 7
Why Seven.
Review — Five and Some More: 8 is 5 and how many?
Answer 3
Why Three.
Warm Up
Straightforward practice. Get the method working first.
3 problemsWhich is bigger, 14 or 18?
Answer 18
Why Eighteen.
Which is bigger, 12 or 17?
Answer 17
Why Seven extras beats two.
Which is smaller, 19 or 11?
Answer 11
Why One extra.
Build It Up
The same ideas with more to keep track of.
2 problemsWhich is bigger, 15 or 13?
Answer 15
Why Five beats three.
Which is bigger, 20 or 16?
Answer 20
Why Two full frames.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
1 problemTwo Jars: One jar has 14 beads, one has 18. Which has more?
Answer 18
Why Eighteen.