4th grade math problem

x + 2x = 48

You have two unknown numbers.

One is x and you figure out the value of the second unknown number by comparing it to the first unknown number.

Twice as many...

So, do this.

2x + x= 48.

2x + x is 3x...

3x = 48

to solve it... divide both sides by 3

x = ?

Then, you have the value of x, but you haven't solved for the question...

Female birds are 2x

Male birds are x...

Got it?

Even easier is dividing 48 by 3. Result is 16 which must be the male portion. Balance for the female is 32.

I'm forgetting my manners. Welcome to a2k. Feel free to ask whatever you will.

Um. Damn bobsmyth. I said the same thing.

Your method has the virtue of being applicable to more complex problems, less sucseptible to immediate intuition.

Thank you. I was using the Republican method: trying to help them see how to do more problems later... You know, teaching to fish, rather than throwing a fish at them, ...so they'd be able to do their homework tomorrow without help...

Just my Republican upbringing....

<winks>

Thanks to both of you! Both of your answers are quite clear and useful...no cause for bickering : ) I guess that you two have squabled over more complex problems than this one...Oh, and thanks for the welcome!

Dear,

Glad it helped. I wasn't squabbling. That was my neighborly persona!!!

Good luck, sweetie.

Math through high school was a BUGGER!!!

I have an idea for you!!!

purplemath.com-------It explains math step by step at all levels.

My son shared it with me--and it has really helped!!!

Good luck!!!

The pedagogical question here sounds interesting enough to warrant a new thread (I choose to avoid the political bait offered .

I don't think introducing the idea of variable ("x") here is not valuable until the student has grasped the problem. The danger is that kids tend to cling to techniques (i.e. assigning variables) instead of understanding ideas (being able to see that the larger group can be divided into two groups leaving you with three equal groups).

Should we start a new thread? or, since the question has been answered, can we discuss this here?

2 gals for every guy---a pretty good mix. But to a fourth grader I'd make this into a two thirds and one third being a whole and then relating the whole to 48. Then I'd show that one third of 48 is 16 and two thirds of 48 is 32.

Rap

If it matters any, I already worked the problem through with my daughter. I went with the 3 parts argument rather than finding the value of x since she has yet to be introduced to any algebra. It was easy for her to grasp the idea that it was 3 equal parts of a whole. Thanks to all of you, this is a great site and I'm sure that I'll be back soon.

How would you explain to a kid why to use 3 or parts of 3?

The same way you would.

The key to the problem is clearly "2x + x". But there are plenty of ways to understand this without using the abstract symbols.

A child can understand that two groups of males is the same number as one group of females, and they can understand that the total number of birds is the sum of the two. To understand this problem they need to understand this, whether or not they use the symbolism or not.

At the fourth grade level, the algebraic symbolism is at best a distraction form the thinking and reasoning skilsl that they should be developing. At worst it is a source of confusion.

An important goal of a good math education is to develop math sense and thinking skills. The problem with jumping to symbolic form is that it focusses on a jumping to a mechanical process before thinking through the problem. This is a bad habit that I saw often in my high school students.

Symbolic algebra also adds cognitive difficulties that at this stage are very difficult for a student to reconcile. For example, the idea of variable is a very abstract concept. A student should be able to grasp the idea of variables before they are used as part of a mechanical problem solving process.

Thanks.

Word Problem
y = male parakeets

2y = twice as many females as there are male parakeets.

Total Number: 48 parakeets.

y + 2y = 48

3y = 48

y = 16

So, there are 16 male parakeets and logically there are 32 female parakeets since 2y = the number of female parakeets and 2 times 16 = 32.

Final answer: 16 male and 32 female parakeets.

I hope this helps.

Feliz

mathman-- They don't like alphabits in these parts.