1.NOS.E.10: 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. Understand that when adding two-digit numbers, tens are added to tens, ones are added to ones, and sometimes it is necessary to compose or decompose a ten. a. Use concrete models and drawings to add. b. Use counting strategies and strategies based on place value (e.g., partial sums, making tens, etc.) to add. c. Use properties of operations, and/or the inverse relationship between addition and subtraction to add. d. Represent and explain the calculation by connecting the strategy used to the meaning of addition.