Number and Operations in Base Ten

1nbt1
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.
1nbt2a
Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1nbt2b
Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1nbt2c
Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1nbt3
Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.
1nbt4
Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit 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 two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
1nbt5
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
1nbt6
Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (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.