Common Core Alignment

CCSS.Math.Content.1.NBT.6 - 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.

5: Math

Unit 7: Place Value
Lesson 14: Working With Multiples of 10
Lesson 15: More Practice With 10
Unit 9: Addition to 100
Lesson 2: Working With 10 Again
Lesson 3: More Practice With Multiples of 10