Measuring Length in Metric

by Laurie Laurendeau on January 31, 2012

Your child will likely be learning about both the U.S. Customary system of measurement, as well as the Metric system of measurement at school.  Today, we are going to concentrate on the Metric system.  The Metric system is used in most countries around the world, and it is the system of choice in the scientific community.  If you are an adult living in the United States, the idea of the Metric system might seem scary, since you probably didn’t learn it when you were in school.  The good news is that the Metric system is a logical, base-ten system that is relatively easy to learn.

We are going to talk about measuring using units in the Metric system.  Next week, we will discuss converting between Metric units.

Ruler Activity:

  • Show your child a ruler.  Most rulers have inches on one side, and centimeters on the other side.  Remind your child that there are two different ways to measure, and that today you are going to talk about the Metric side.  One of the Metric units is called the centimeter.
  • Show your child how big a centimeter is on the ruler.  Now, have her place her baby finger in the space.  A centimeter is about the width of your baby finger.  Place your baby finger in the same space (it’s just interesting to see that as we get older, the width of our baby finger doesn’t change a lot, so an adult (woman’s) baby finger is about a centimeter wide as well).
  • Find some objects around the room that your child could measure in centimeters.  Try to choose objects that are shorter than the ruler you are using for ease of measuring.
  • Once your child has had a lot of practice measuring objects around the room using centimeters, look around the room and ask your child to estimate how many centimeters he thinks certain objects measure (ex: a book, a pencil, a coaster).
  • Next, introduce the millimeter.  There are 10 millimeters in a centimeter.  Have your child place a pencil tip on the ruler.  This is about a millimeter.  Tell your child that because the millimeter is so small, it takes a lot more millimeters than centimeters to measure something.  Again, practice measuring objects around the room, but this time report your findings in millimeters.  You might want to measure some of the same items you measured in centimeters to compare the difference between its centimeter measure and its millimeter measure.
  • Finally, if you have a meter stick, show it to your child.  A meter is 100 centimeters, or 1,000 millimeters.  Tell your child that you would measure longer objects with a meter stick.  Practice measuring various objects.  If you do not have a meter stick, and you have a ruler that is a standard length of 30 centimeters, you could lay out 4 rulers in a row and place a marker at the 100 centimeter mark to show how long a meter would be.


  • As always, playing math games at home is a great way to reinforce math skills learned in school.
  • Have questions or ideas about this story?
  • Need help or advice about your child’s learning?
  • Have ideas for future Parent Homework Help stories?

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