U2_rocks!
<font color=coral>The DISer formerly known as U2_r
- Joined
- Sep 7, 2006
- Messages
- 3,469
When I first started high school there was a teacher that was telling the class about tricks to do math in your head faster. She would have someone put up
85 + 30 + 24 = ??
and challenge someone to beat her to the answer. I was always about on par with her but most of the kids were way behind.
She then told about the method that is here. I had just always done that. I would say 85 + 15 is 100 and 15+24 is 39 so 139.
So a bunch of people found a way to do math faster in their head out of that lesson. I learned that the rest of the class didn't think that way. I always thought they had (and wondered why everyone else was so slow... It never occured to me they were doing 85
+ 30 is 5+0 is 5 and 8+ 3 is 11 so 115 + 24 so 5+4 is 9 and 2+1 is 3 and 1+0 is 1 so 139.
Edit to add:
I will however agree that there is a time that may be too early to teach this. Because if a child is still struggling with doing it the old way now they will be REALLY lost. Once you get the old way really well the new way is better... but not if it means someone never really masters either way.
In our schools children learn "mental arithmetic" from ages 7 - 11. They learn all sorts of different tricks for arriving at the answer, but they learn them mentally - they don't have to set out all these written workings that look confusing. My kids are now between 11 and 14, and they are doing more complicated math problems. When I am helping them I can see how they each have a preferred method of working out calculations in their heads. My son likes to work in 10s as much as possible. My 11 year old likes to count up. I don't know what my 13 year old does - she's the fastest of them all (faster than I am at times and that's saying something!), and I'm not sure she even stops to think about her methods.
I think it's important for kids to understand numbers and how they work fully. I can tell you though that my son would be lost if he had to look at a long written illustration of something simple - he learns better from hearing and practising, which is why the mental arithmetic worked brilliantly for him. My 13 yo would have learned it no matter how you taught it. My 11 yo is somewhere in between. I hope US schools aren't using only those long written illustrations to teach math concepts - I hope they are using other methods as well.