This is a week long unit (20-30 minutes/day) covering adding and subtracting 10 is aligned to the CC standard 1.NBT.5. I have used this with my 1st graders with great success! There is mathematical reasoning, practice problems, manipulative use (hundreds chart) and higher level questioning. Each days lesson also comes with a Ticket Out the Door to do a quick mastery assessment. There will be more Common Core aligned math lessons posted to my store using the same format and vocabulary!