MA 02.NBT.B.5 Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
—-
Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
Good Projects here: Illustrative Mathematics https://www.illustrativemathematics.org/content-standards/2