Mental Math - Please explain


Mental Math - Please explain

Unread post by cbollin » Fri Apr 25, 2008 1:56 pm

RachelT wrote:Hi! What do people really mean when they say that Singapore is "mental math"? I have heard so many people say that, but I don't know what they really mean.
Posted: Thu Nov 15, 2007

Good question Rachel. I had the same one especially considering that I kept seeing on some pages something called "mental math" on those MUS pages. For a long time (even on this board), I kept saying "but wait a minute… doesn’t MUS do mental math??? Huh???" Not really. What MUS calls "mental math" is just a quick way to practice some drills out loud and is a tag on at the bottom of some worksheets.

I’ll try to a bit with that definition of mental math from my Singapore use.

When I heard others talk about Singapore Math's mental math, it was almost a disservice. It makes it sound like you do all computations and arithmetic in your head or that somehow you never use manipulatives or other concrete teaching methods. I knew I was missing something because after all, Singapore Math is a very visual math program. Mental Math in Singapore is about the thought processes of solving a math problem rather than just plugging and chugging through a problem and learning how to put the information in a formula and solve it.

This gets played out both in computation problems as well as word problem. One example from the computation aspect includes how Singapore helps to teach addition and subtraction with regrouping so that you don’t have to always stack it on top and borrow from the tens and write it out. That method is also taught, but after you work with your student to show them why it is going to work.

With word problems the mental math helps to think about the problem not just writing down an equation and solving it. And it really does help the student to think and almost see the answer on some problems without writing much on paper. But there’s nothing wrong with writing stuff down too.

Example from my oldest child's work just yesterday. (She's in level 6B and was working on a Review page at the end of the first unit.) The problem went like this: Ryan withdrew ¼ of his savings from the bank. He spent $450 of it and had $150 left. How much was his savings in the bank at first?

My daughter just wrote down the answer. I looked at her and said “do you want to show your work or just tell me how you did that?” Oldest said “well, they practically just tell you the answer. $600 (450 +150) is 1 out of 4 bars. 4 bars of 600 is 2400.”

She really had a good mental hold of the problem. She wasn’t trying to write anything like ¼ x = 600 and then solve it from there. Now if only her 4’s didn’t look like a 9. sigh. <grin>

So – learning to think about the problem instead of just starting to write down numbers and symbols is what makes up the biggest part of “mental math in Singapore”

Now… not all of her problems can she do in her head. She will draw her own bar diagrams and think out loud on paper and have to do pencil and paper math. I do want to make sure that is said.



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