Extracting Square Roots - L 110 in R&S Math 8...

[Highland61996]

My ds came across this lesson dealing with extracting square roots in his R&S Math 8 textbook, and was quite confused over the explanation. Their explanation confused me as well. Is there anyone else who has used R&S math 8 who can help clarify how to go about teaching this? How important is this for him to understand this concept now? Does he need it before algebra I? Thanks.

[regentrude]

I do not have r&S, but if you could post what you mean by "extracting square roots" (i.e. an example), I might be able to help.

[JanetC]

I don't have R&S either, but I think you are talking about simplifying radicals?

 

http://www.khanacademy.org/math/algebra/exponents-radicals/v/simplifying-radical-expressions1

 

If the above examples are too advanced, try this instead:

 

http://www.khanacademy.org/math/algebra/exponents-radicals/v/simplifying-square-roots

 

Another possible resource is here--

 

http://www.artofproblemsolving.com/Videos/index.php?type=prealgebra#chapter9

[Beth in SW WA]

My ds came across this lesson dealing with extracting square roots in his R&S Math 8 textbook, and was quite confused over the explanation. Their explanation confused me as well. Is there anyone else who has used R&S math 8 who can help clarify how to go about teaching this? How important is this for him to understand this concept now? Does he need it before algebra I? Thanks.

 

The videos on this page may help. This

is fantastic. :)

[Julie in MN]

I do not have r&S, but if you could post what you mean by "extracting square roots" (i.e. an example), I might be able to help.

 

:iagree:

 

I would assume they either mean "finding the square root" or they mean a little more complex cases of "reducing the square root." In either case, likely it will just be helpful if the student understands what a square root and a square mean before algebra. There should be plenty of practice with using them during algebra I and II.

 

Julie

[wapiti]

more square root videos, FWIW

 

Square Root Introduction Part 1

Square Root Introduction Part 2

Non-Integer Square Roots

Square Root of a Product

Sum of Square Roots

Simplifying Square Roots Part 1

Simplifying Square Roots Part 2

[KAR120C]

My ds came across this lesson dealing with extracting square roots in his R&S Math 8 textbook, and was quite confused over the explanation. Their explanation confused me as well. Is there anyone else who has used R&S math 8 who can help clarify how to go about teaching this? How important is this for him to understand this concept now? Does he need it before algebra I? Thanks.

I know of two methods, but before algebra they'd only be taught as rote algorithms.

 

As long as he knows his squares up to 10^2 (or better yet to 20^2), and how to simplify a radical expression, I would save extracting more complicated roots for after algebra. The method I prefer relies on being able to manipulate a series of (a + b)^2 = a&2 + 2ab + b^2 equations... and I wouldn't expect that until after a year of algebra.

[Highland61996]

In answer to what regentrude asked, this is what his math book said: "The square root of a number that is not on the table (table in the book index) can be found through the process known as extracting the square root. This process is somewhat similar to division." Then it went on to give 8 steps to follow to find the square root. In the next lesson it says, "The process of extracting square roots can be used when the radicand is not a perfect square. A square root can be calculated to as many decimal places as desired, the same as the quotient of a division problem." Then he was given 4 or 5 digit numbers to find the square roots.

 

Thank you for all of the suggestions given here. We had already come across a previous thread with links to AoPS videos, so we watched those. We'll look at some of the links in the threads here and see what we can figure out.

[KAR120C]

In answer to what regentrude asked, this is what his math book said: "The square root of a number that is not on the table (table in the book index) can be found through the process known as extracting the square root. This process is somewhat similar to division." Then it went on to give 8 steps to follow to find the square root. In the next lesson it says, "The process of extracting square roots can be used when the radicand is not a perfect square. A square root can be calculated to as many decimal places as desired, the same as the quotient of a division problem." Then he was given 4 or 5 digit numbers to find the square roots.

 

Thank you for all of the suggestions given here. We had already come across a previous thread with links to AoPS videos, so we watched those. We'll look at some of the links in the threads here and see what we can figure out.

The description that it's "similar to division" sounds like this method: http://mysite.du.edu/~jcalvert/math/sqrt.htm

 

I honestly wouldn't bother with it at this point. He could learn it as a rote algorithm, but without a fair bit of algebra under his belt I think it would just be a parlor trick. Better than that is to be able to estimate (like the AoPS videos show), or to factor out what you can and reduce the radical expression.

[Colleen in NS]

How important is this for him to understand this concept now? Does he need it before algebra I?

 

My math-loving son (being taught by his math-understanding father) used R&S 8 last year, and is using an old Dolciani Algebra I book this year. In the past few weeks (so, near the *end* of his algebra book), he has been learning about extracting and reducing square roots. I told him about your post, and he says that his algebra book taught him from scratch, and it taught him a different method than the R&S 8 book did. He said the method taught in the algebra book made more sense to him, too. He thinks that if he'd never learned the R&S 8 method, it wouldn't have mattered to his algebra learning (at least in this particular algebra book).

 

hth

[Highland61996]

Thanks Colleen. That's good to know.

We watched two or three more online videos about square roots today. I think we'll move on after this.