Common Core Alignment

CCSS.Math.Content.1.NBT.2.a - 10 can be thought of as a bundle of ten ones — called a "ten." b.

5: Math

Unit 7: Place Value
Lesson 1: What Is the Base-10 System?
Lesson 2: What Is Place Value?
Lesson 3: Tens
Lesson 4: Distinguishing Tens and Ones