Fourth grade math question... What do you make of this?

[Microcell]

DD is working on her math homework and this is the question:

How would you regroup 4 tens to find the difference between 341 and 228?

We are stumped!

Any advice?

 

[Kathi OD]

DD is working on her math homework and this is the question:

How would you regroup 4 tens to find the difference between 341 and 228?

We are stumped!

Any advice?

In 341, you regroup the 4 tens to 3 tens and add the other 1 ten to the ones or units place, giving you 11 ones.

 

[kribit]

Are you kidding me? I better enroll in a math class....and fast.

 

[Microcell]

So Kathi, you think what they want is a detailed explination of how to subtract by changing the the 4 to 3 and carrying over the one?

In other words a step by step detail on how to subtract?

Could it be that easy?

 

[CrazedDisFan]

Yes, step by step on regrouping to subtract.

Fourth grade math is made to confuse parents.

 

[ShuisFan584]

Geez, I'm an actuary who majored in math in college. I've done the most difficult math in courses in school, and on actuarial exams. Math is my subject....and I didn't understand what this question meant!

I'll be embarassed when my kids come to me with questions like this for homework and I can't answer!

 

[Kathi OD]

So Kathi, you think what they want is a detailed explination of how to subtract by changing the the 4 to 3 and carrying over the one?

In other words a step by step detail on how to subtract?

Could it be that easy?

YEP! Having taught 4th grade math, I'm almost certain that this is what they are looking for.

Today math is so much more focused on the reasons why math works than it was years ago. The thinking is that if children understand why, then the how will be easier because there is some logic behind it.

When I was in grade school (literally back in the stone age), all we were taught was the mechanics or algorithm. None of us really understood why we had to borrow. We weren't really taught the concept of place value and how it was connected to borrowing in subtraction or carrying in addition. Now there is more focus on "regrouping" rather than borrowing or carrying, because in both instances that's what is really happening...the numbers are regrouped. The numbers still have their same original value, just expressed in a different way in order to expedite the arithmetic.

I hope I made sense.....I feel like I might have just confused the issue.

 

[Microcell]

Color me confused! It is embarrassing!

Now her eye hurts... Does this mothering ever end??

Thanks so much to all of you!

 

[MomofKatie]

I have a 4th grader, too, and I am embarrassed to admit that I am regularly confused by her word problems. They seem to be very "algebraic", and I was awful in algebra.

The stumper from Tuesday (we had to call her dad out of town- he solved it in about 30 seconds ):

The difference between two numbers is 2184. If the larger of the two numbers is three times the smaller number, what is the sum of the numbers?

I sat and scratched my head over that one for about half an hour.

 

[Kathi OD]

I have a 4th grader, too, and I am embarrassed to admit that I am regularly confused by her word problems. They seem to be very "algebraic", and I was awful in algebra.

That's another thing that is "newer" in math classes. Teaching algebraic thinking at a younger age helps students when they are actually taking algebra. It should start even in earlier grades with problems similar to this: 14 plus what number equals 35, or What number subtracted from 18 equals 5.

 

[Charade]

I don't know why there's so much emphasis on these types of math equations. All they need to do is teach them how to make change. "Do you want fries with that?"

 

[Kathi OD]

I don't know why there's so much emphasis on these types of math equations. All they need to do is teach them how to make change. "Do you want fries with that?"

The emphasis is for understanding the process involved. If you're someone who is just "good at math", it wouldn't make sense. BUT, for those of us who aren't so "good at math," it helps when you understand why you are doing things. Hopefully, it will help them to get beyond just needing to know how to make change.

 

[bumbershoot]

The difference between two numbers is 2184. If the larger of the two numbers is three times the smaller number, what is the sum of the numbers?

I sat and scratched my head over that one for about half an hour.

3640? And that answer is only if it's the sum of the larger and the smaller numbers (as DH thinks), rather than the sum of all numbers mentioned in the problem (as I think).



I have to tell you guys....4th grade math almost ruined me. I had an excellent teacher, I was at a tiny school (a schoolhouse, really), where I was tested to be reading at a 13th "grade" level and did very well in everything else. But 4th grade math (stinkin' long division) devastated me. And how I felt about that started the "stupid-i-fication" I did to myself that shunted me right out of the Gifted programs I had been a part of, and I only pulled myself out of things at the end of my Sophomore year of HS (had a "cannot take this anymore" moment in English and insisted they put me in honors English and History).

It's hard to imagine that they found a way to make 4th grade math harder and weirder for brains that can't think that way...but it appears that they did. Odd.

 

["Got Disney"]

I cant seem to get my kids Math....I try to help them with the way I learned and they say..No mom thats not the way we do it know.....

to me 5 + 5 will always be 10......not something crazy.

 

[Kathi OD]

3640? And that answer is only if it's the sum of the larger and the smaller numbers (as DH thinks), rather than the sum of all numbers mentioned in the problem (as I think).

1. Well difference means the answer in a subtraction problem.

2. So you've got some number minus some other number equaling 2184.

3. You also know that of the two numbers you are subtracting, one is 3 times larger than the other, so you give the smaller number the "x" value because you don't have any information about it.

4. The other number (the larger one) becomes 3x, because you know it is 3 times larger than the other number.

5. So your equation becomes 3x - x = 2184

6. Next you "do" the subtraction. If you have 3 and take 1 away, you have two.

7. 2x = 2184

8. To undo the multiplication in 2x you have to divide by 2. Since you divide by two on the left side of the equation, you have to do the same on the right side. 2x/2 = 2184/2

9. After dividing you get x = 1092

10. So now you know how much the smaller number is (1092).

11. To find the larger number multiply 1092 by 3 (3276).

12. The problem asked for the sum of the numbers, it means the two unknowns. So 3276 + 1092 = 4368

It's hard to imagine that they found a way to make 4th grade math harder and weirder for brains that can't think that way...but it appears that they did. Odd.

Part of the reason why it seems harder to you is because you were only taught the algorithm and not the reasons why it all worked. That's where schools today are different. When children who are not "good at math" can understand the "why" of numbers, they become better at the "how" of numbers. Understanding the "why" makes the "how" more meaningful.

 

[Kathi OD]

[QUOTE="Got Disney";21370471]I cant seem to get my kids Math....I try to help them with the way I learned and they say..No mom thats not the way we do it know.....

to me 5 + 5 will always be 10......not something crazy.[/QUOTE]

Don't worry, it's still 101

 

["Got Disney"]

Don't worry, it's still 101

seems more like Math 210...than 101... basic math still has the same concept just a different way of doing it.

 

[Kathi OD]

[QUOTE="Got Disney";21370624]seems more like Math 210...than 101... basic math still has the same concept just a different way of doing it.[/QUOTE]

That was a typo in there. It was just supposed to say 10. That extra 1 really does give a different meaning!

 

[pooksma]

I had to jump in here as a seventh grade math

More and more emphasis is placed on the "how" in today's math, as a previous poster stated. This is great, up to a point. The problem we are encountering (pardon the pun) now is that students don't know their basic facts anymore. Timestables are a complete nightmare when you are trying to teach exponents to kids who can't tell you that 7 x 7 = 49.

After 10 years I am still trying to find a way to balance the two methods. And I was one of those kids that couldn't "do" math so i appreciate where they are coming from. That said, I did know my basic facts.

 

[Maleficent13]

See...I'm not sure I agree with the concept of "why". To me, if you are not a math whiz, it's easier to memorize the algorithm and just *know* it. I can see a kid becoming quickly frustrated with a 74 step subtraction problem.

I also have to say, for all this new method, it's the younger people who learned with the new method that can't make change, not the older people who learned the old-fashioned way. Possibly because they need a pencil and paper to write out their algebra equation for 5.00 - 2.50 = 2.50.

As always, JMHO, YMMV.