1. Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings,
and equations with a symbol for the unknown number to represent the problem (Students are not required to independently read the word problems.) 
2. Apply properties of operations as strategies to add and subtract. Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. 
3. Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem. 
4. Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. 
5. Determine the unknown whole number in an addition or subtraction equation relating to three whole numbers. 
6. Understand that the two digits of a two-digit number represent amounts of tens and ones. 
7. 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.