Math help: decimals

[Buckalew11]

DD is converting metric measurements for homework. She is having trouble knowing how to move decimals.

For example: How many meters are in 1,969 centimeters. Which direction do you move the decimal, left or right?

She seems to be getting the right answers but I think she needs to know why she is doing what she is doing. This was just a worksheet sent home by the teacher w/o the teacher going over this lesson. Of course, y'all know, I am of NO help when it comes to math.
TIA

 

[LadyyRedd]

When you are converting from a smaller unit to a larger unit, you move the decimal to the left.

IE. 1969 cm to how many m, you would the decimal to the left to get 19.69 m.

When you are converting from a larger unit to a smaller unit, you move it to the right.

IE, 19.69 m to cm would be 1969.

Kimya

 

[nuke]

Every meter contains 100 centimeters. To convert centimeters to meters you divide by 100. To convert meters to centimeters you multiply by 100.

 

[Wazzo]

Check out this website if you and your child are visual learners...

http://facweb.bhc.edu/academics/science/harwoodr/Geol101/Labs/Metric/

There's a nice diagram under "Metric System Conversions", and it labels the order of converions from kilometres right down to millimetres.

Good luck!

 

[Buckalew11]

Thanks to you both!

I think it was not clicking with "why am I doing this?" I hope the teacher sending home this paper w/o going over it isn't a sign of what the year will be like. I have a horrible math phobia and am useless when it comes to math.

 

[golfgal]

AARRRUUUGGGGHHHHHH, HOMEWORK!!!! I am not ready for homework yet!!! I am still on vacation!

 

[Sparx]

I remember this with

Kangaroos Hopping Down Gardens Drinking Chocolate Milk

kilo, hecto, deca, grams, deci, centi, milli.

(grams interchangable with meters and leters.)

You start at centi and you go backwards until you hit meters. Thats 2 backwards, so you move the decimal 2 places to the left.

 

[#1hockeymom]

Have her memorize the order.... ie millimeter, centimeter, decimeter, meter
*remember millipedes have lots of legs... centipedes less!

as you're moving from place to place you say the place value


Have her also look at the size...
mm=dime width
cm= index finger width
dm= palm width
meter= bigger than a yard

Have her think about if the number to fill the length should be bigger or smaller... obviously more centimeters are needed to fill a meter than the one meter. Have her check her answers with that knowledge in her head to make sure her answers make sense.

The movement of the decimal point was well described in previous posts.

I hope this helps!

 

[#1hockeymom]

Sparx! I love your version to memorizing the order! I will use this in my class!

 

[Sparx]

Sparx! I love your version to memorizing the order! I will use this in my class!

I learned that in fifth grade I think. You can also switch gardens for libraries or museums. I've also got one for memorizing species orders if you teach science.

 

[Buckalew11]

Wow! You all are a lot of help! This is review from last year but I don;t think she ever knew why she was doing it (& I don't think she understood the measurements and how big they were. I don;t even remember it from last year so I don;t think it was an issue but then as she was reviewing it, with no review from her teacher, I think she was very confused about which direction and why!

Thank you everyone and to sparx for the little sentence. I know she was telling me one about Aunt Sally that I had never heard before!

Oh, and I am sure we'll will be back for more help. You haven't heard the last of me!

 

[Sparx]

Thank you everyone and to sparx for the little sentence. I know she was telling me one about Aunt Sally that I had never heard before!

Please Excuse My Dear Aunt Sally.

That helped me so much when I was in sixth grade.

 

[DisneyCP2002]

Here is one I used when learning converting decimals:

King Henry danced merrily down center main

 

[Buckalew11]

Please Excuse My Dear Aunt Sally.

That helped me so much when I was in sixth grade.

That was it! Yeah, it would have helped me in sixth grade and 7th and 8th... I am not sure how I got through Algebra without understanding the rules?? I wish I could go back and do it all again. I think I'd get it this time!!

 

[Fire14]

I always used "kids have dropped over dead converting metrics". Over being you meter, gram, whatever other one is.

 

[Buckalew11]

DD's sixth grade math teach told her:
King Hector Died by Drinking Chocolate Milk
(kilo hecto deca base deci centi milli)
This too would have helped me.

 

[Simba's Mom]

Remember "L"arger-"L"eft. I'm very much into alliteration (I think that's what you call it) to remember things. Even as adults, I hear my math students remembering aloud "D"enominator-"D"own to remember the denominator vs. numerator in a fraction.