New York State Learning Standards and Core Curriculum
NY-1.NBT. Number & Operations in Base Ten
Understand place value.
NY-1.NBT.2. Understand that the two digits of a two-digit number represent amounts of tens and ones.
NY-1.NBT.2a. Understand 10 can be thought of as a bundle of ten ones, called a "ten".
NY-1.NBT.2b. Understand that the numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
NY-1.NBT.2c. Understand that 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).