Comparing Metric Measurements

Date: 09/22/2005 at 19:38:58
From: Chanel
Subject: I don't know which is heavier like 900g or 1kg

How do I decide which is heavier, 900g or 1 kg?  I'm in 6th grade and
I just came to a new school and my old school didn't explain this so I
was wondering if you could help me figure out this problem?

Date: 09/22/2005 at 21:23:41
From: Doctor Peterson
Subject: Re: I don't know which is heavier like 900g or 1kg

Hi, Chanel.

If you haven't been taught the metric system, and your teacher is 
about to use it, it might be a good idea to ask your teacher for a 
quick introduction to it.  If you'd rather do it yourself, and can't
find a good book that covers it in your library, try this site:

  Metric Measurements
    http://mathforum.org/library/drmath/sets/select/dm_metric.html 

and the links there.  I haven't found a really good site that explains
the system from scratch, without going too deep for you.  Here is a
good summary, as long as you know you aren't expected to know much of it:

  The International System of Units
    http://lamar.colostate.edu/~hillger/brownridge.html 

I'll summarize the main ideas.  At an elementary level, there really
isn't much to learn, just a lot of practice to get good at it.

In our common American system of measurements, everything is pretty
haphazard; there are 12 inches in a foot, 16 ounces in a pound, 2 
pints in a quart, and so on.  The metric system is easier, because for
each kind of measurement, there is one basic unit, and the same ways
to change that unit to larger or smaller ones.  The basic units are

  length: the meter (about a yard)
  weight: the gram (a nickel weighs about 5 grams)
  volume: the liter (about a quart)

To name a larger or smaller unit, we add prefixes before the unit name:

  kilo-: thousand
  centi-: hundredth
  milli-: thousandth

and a lot of others that aren't used quite as much.

Putting these two simple ideas together,

  1 kilogram = 1 thousand grams = 1000 grams

  1 millimeter = 1 thousandth of a meter = 1/1000 meter

and so on.

Oh, you'll need one more thing, before you can answer your problem:
the symbols (abbreviations) for the units and prefixes.  The page I
referred to above lists many of them, but here's what you need to start:

  meter  = m
  gram   = g
  liter  = L

  kilo-  = k
  centi- = c
  milli- = m

So a kilogram is a kg, and a millimeter is a mm.  

If you have any further questions, feel free to write back.


- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/