Common Core Mathematics K2  Cluster  Understand place value.   Grade 1   1.NBT.2.  Understand that the two digits of a twodigit 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.3.  Compare two twodigit numbers based on meanings of the tens and ones
digits, recording the results of comparisons with the symbols >, =, and <. 
