3.NBT.2 Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
Provided on the page are 10 answers to subtraction problems. Students must create their own 3 and 4 digit subtraction problems with regrouping and subtraction across zeros that result in the difference given. After they create their problem, they must also show the inverse operation. As students begin puzzling through the first problems, they slowly begin to figure out how to use their knowledge of inverse operations to create their problems. My higher level and talented and gifted students loved this challenge. It proved to exercise and engage their brains and really helped solidify their understanding and appreciation for inverse operations.