Math is taught so differently now than when most adults learned it! That's because our world is so different now than when current adults were children! The focus is so much more on gaining deep understanding of mathematical processes rather than simply memorizing facts. If your child learns a way to add or subtract in a way you don't know, one of the best things you can ask them to do is to teach you! It will reinforce their own understanding of the alogrithm. Teaching is a great way of learning.
In addition, try these:
- "Does your answer make sense?" Ask this even when an answer is correct! It helps children practice reasoning skills and justifying their answers. It makes them stop and consider if their answer is reasonable.
- "Would 100 (or 3 or 50 1/2 or -9, etc.) make sense in this problem?" Why or why not?
- "What number would NOT make sense in this problem?" Again, this will help students think deeply about numbers, and gain what we call "number sense".
- Solve a problem incorrectly intentionally. Then ask your child to find your error. It's much more challenging than having them simply solve problems on their own.
- "Explain in words how you solved this problem." This is a common skill students are learning in all grades. Communicating their thinking is just as important as computing. If students struggle with this skill, and many do, try having them tell you what they did while you write it for them, or record themselves saying what they did, and then listen back to it. Many times, saying it is not too hard, but writing it is challenging.