Luyện nghe bài hát New Math

Some of you who have small children may have perhaps been put in the embarrassing position of being unable to do your child's homework because of the current revolution in mathematics teaching known as the new math.

So as a public service here tonight I thought I would offer a lesson in the new math. tonight we're going to cover subtraction. this is the first room I've worked for
a while that didn't have a blackboard so we will have to do with more primitive visual aids, as they say in the "Ed biz." consider the following subtraction problem, which I will put up here 342 - 173.

Now remember how we used to do that. three from two is nine; carry the one, and if you're 35 or went to a private school you say seven from three is six, but if you're over 35 and went to public school you say eight from four is six; carry the one so we have 169, but in the new approach, as you know, the important thing is to understand what you're doing rather than to get the right answer here's how they do it now.

You can't take three two,
Two is than three,
So you look at the in the tens place.
Now that's four tens,
So you make it tens,
Regroup, and you a ten to ten ones,
And you add to the two and get twelve,
And you take three, that's nine.
Is that

Now instead of four in the place
got three,
'cause you one,
is to say, ten, to the two,
But you can't seven from three,
So you in the hundreds place.

the three you then use one
To ten ones...
(and you know why four plus one
Plus ten is fourteen one?
addition is commutative, right.)
And so you thirteen tens,
And you take seven,
And that five...

Well, six actually.
the idea is the thing.

Now go to the hundreds place,
And you're left two.
And you away one from two,
And leaves...?

get one?
Not bad for the day!

for new math,
New-hoo-hoo-math,
It won't do you a bit of good to math.
so simple,
So simple,
That a child can do it!
Now that is not the answer that I had in mind, because the book that I got this problem out of wants you to do it in base eight. but don't panic. base eight is just like base ten really
if you're missing two fingers. shall we have a go at it? on.

You take three from two,
Two is less three,
So you look at the in the eights place.
Now that's really eights,
So you it three eights,
Regroup, and you change an eight to ones,
And you add to the two,
And you get base eight,
is ten base ten,
And you away three, that's seven.

Now of four in the eights place
got three,
'cause you one,
is to say, eight, to the two,
But you can't take seven three,
So you at the sixty-fours.

"sixty-four? how did get into it? " I hear you cry.
Well, sixty-four is eight squared, don't you
(well, you ask a silly question, and you get a answer.)

the three you then use one
To make ones,
And you add ones to the three,
And you get one-three eight,
Or, in words,
In base ten you eleven,
And you take seven,
And seven from is four.
Now go to the sixty-fours,
And you're left two,
And you away one from two,
And leaves...?

Now, let's not see the same hands.
One, right!
Whoever got one can stay the show and clean the erasers.

for new math,
New-hoo-hoo-math,
It won't do you a bit of to review math.
so simple,
So simple,
only a child can do it!

Come back tomorrow night. we're do fractions.