We have been working hard learning all sorts of strategies for adding math facts to 20. I would like to explain some of them here so your can see if your child either knows those fact families or at least knows how to use the strategy. This is the stage where I am teaching the children how to figure out addition facts without simply counting. As far as subtraction goes, it is the goal that once the students learn the "fact family" by memory, they will recognize the difference by knowing the fact family. For example, the children now know their addition doubles by memory so in turn are starting to recognize a "doubles fact" when they see the reverse in subtraction. I can say 14-7 and they know the answer is 7 because "I know 7+7=14."
These are the strategies we have been working on.
1. Doubles- I think all the kids know these by memory.
2. Teams of ten- the various combos of numbers that add up to 10. It is expected in grade two that all kids know these by memory.
3. Near doubles- using either double plus one or doubles minus one for a fact.ex 7+8 is 7+7 +1 or 8+8-1
4. Make or use a ten- this involves +9 or even +8.. Any number adding 9 we pretend the 9 is a 10, so add 10 then take away 1. Or said another way, 9+7 just borrow 1 from the 7 to make a 10 with the 9, then you have 10 + 6=16.
5. Use a known fact- Sometimes certain facts just stand out for kids. If your child has 4+7 memorized then they use it to solve 5+7.
We have other strategies as well but these are the important ones. All this great brain work is called mental math. Thursday I taught the kids a type of solitaire card game which involves adding numbers. See if they can show it to you at home. It is a really great game for practicing number facts.
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