This is a great review activity for multi-digit addition and subtraction 4NBT4.
There is a section where they do addition and subtraction that requires borrowing and regrouping, a section where they do addition and subtraction that does not require borrowing and regrouping, and a section where they find and correct mistakes that have been made.
It all circles around an exciting theme that they are secret agents for the US government and are completing missions and recovering items.
Extra materials you will need:
Envelopes or ziploc bags (optional)
3-6 folders (required)