Every student is at their own place with their understanding if this concept. Come children are working on fact families 0-5, 0-10, 0-20, 0-100. Sometimes they roll dice and use those numbers to make a fact family, using 4 true equations to prove their thinking.
An extension would be give the sum and have them create a fact family using 4 true equations.
Students, no matter where they are in their development, love to be challenged. YAY for math workshop and opportunities to push our own understanding through discovery and sharing with friends!
