Common Core Alignment:.

1.NBT.2:

Number And Operations In Base Ten

Understand Place Value.

Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:

a. 10 can be thought of as a bundle of ten ones - called a "ten."

b. The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.

c. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).

1.NBT.2a:

Number And Operations In Base Ten

Understand Place Value.

10 can be thought of as a bundle of ten ones - called a "ten." b.

1.NBT.2c:

Number And Operations In Base Ten

Understand Place Value.

The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).

K.NBT.1:

Number And Operations In Base Ten

Work With Numbers 11-19 To Gain Foundations For Place Value.

Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.