Understand that the two digits of a two-digit number represent amounts of tens… | Understand that the two digits of a two-digit number represent amounts of tens and ones.<ul><li>Unitize by making a ten from a collection of ten ones.</li><li>Model the numbers from 11 to 19 as composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.</li><li>Demonstrate 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, with 0 ones.</li></ul> | NC.1.NBT.2 |
Compare two two-digit numbers based on the value of the tens and ones digits… | Compare two two-digit numbers based on the value of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <. | NC.1.NBT.3 |
Using concrete models or drawings, strategies based on place value, properties… | Using concrete models or drawings, strategies based on place value, properties of operations, and explaining the reasoning used, add, within 100, in the following situations:<ul><li>A two-digit number and a one-digit number</li><li>A two-digit number and a multiple of 10</li></ul> | NC.1.NBT.4 |
Given a two-digit number, mentally find 10 more or 10 less than the number… | Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. | NC.1.NBT.5 |
Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range… | Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90, explaining the reasoning, using:<ul><li>Concrete models and drawings</li><li>Number lines</li><li>Strategies based on place value</li><li>Properties of operations</li><li>The relationship between addition and subtraction</li></ul> | NC.1.NBT.6 |