Topic: Number and Operations in Base Ten  Common Core Mathematics K2   Cluster Work with numbers 11–19 to gain foundations for place value.    Kindergarten     K.NBT.1.  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.   Cluster Extend the counting sequence.    Grade 1     1.NST.1.  Count to 120, starting at any number less than 120. In this range, read
and write numerals and represent a number of objects with a written
numeral.   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 <.   Cluster Use place value understanding and properties of operations to add
and subtract.    Grade 1     1.NBT.4.  Add within 100, including adding a twodigit number and a onedigit
number, and adding a twodigit number and a multiple of 10, using concrete
models or drawings and strategies based on place value, properties of
operations, and/or the relationship between addition and subtraction;
relate the strategy to a written method and explain the reasoning used.
Understand that in adding twodigit numbers, one adds tens and tens, ones
and ones; and sometimes it is necessary to compose a ten.     1.NBT.5.  Given a twodigit number, mentally find 10 more or 10 less than the
number, without having to count; explain the reasoning used.     1.NBT.6.  Subtract multiples of 10 in the range 1090 from multiples of 10 in the
range 1090 (positive or zero differences), using concrete models or
drawings and strategies based on place value, properties of operations,
and/or the relationship between addition and subtraction; relate the
strategy to a written method and explain the reasoning used.   Cluster Understand place value.    Grade 2     2.NBT.1.  Understand that the three digits of a threedigit number represent amounts of hundreds, tens, and ones; e.g., 706 equals 7 hundreds, 0 tens, and 6 ones. Understand the following as special cases:
a. 100 can be thought of as a bundle of ten tens −called a "hundred."
b. The numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones).
    2.NBT.2.  Count within 1000; skipcount by 5s, 10s, and 100s.     2.NBT.3.  Read and write numbers to 1000 using baseten numerals, number
names, and expanded form.     2.NBT.4.  Compare two threedigit numbers based on meanings of the hundreds,
tens, and ones digits, using >, =, and < symbols to record the results of
comparisons.   Cluster Use place value understanding and properties of operations to add
and subtract.    Grade 2     2.NBT.5.  Fluently add and subtract within 100 using strategies based on place
value, properties of operations, and/or the relationship between
addition and subtraction.     2.NBT.6.  Add up to four twodigit numbers using strategies based on place
value and properties of operations.     2.NBT.7.  Add and subtract within 1000, using concrete models or drawings
and strategies based on place value, properties of operations, and/or
the relationship between addition and subtraction; relate the strategy
to a written method. Understand that in adding or subtracting threedigit
numbers, one adds or subtracts hundreds and hundreds, tens
and tens, ones and ones; and sometimes it is necessary to compose or
decompose tens or hundreds.     2.NBT.8.  Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.     2.NBT.9.  Explain why addition and subtraction strategies work, using place value
and the properties of operations.[Explanations may be supported by drawings or objects.] 
