A standard unit of measurement provides a reference point by which objects of weight, length, or capacity can be described. Although measurement is an important part of everyday life, kids don't automatically understand that there are many different ways to measure things.

### Standard vs Nonstandard Units

A standard unit of measurement is a quantifiable language that helps everyone understand the association of the object with the measurement. It is expressed in inches, feet, and pounds, in the United States, and centimeters, meters, and kilograms in the metric system. Volume is measured in ounces, cups, pints, quarts, and gallons in the U.S. and milliliters and liters in the metric system.

In contrast, a nonstandard unit of measurement is something that may vary in length or weight. For instance, marbles are not reliable for finding out how heavy something is because each marble will weigh differently than the others. Likewise, a human foot cannot be used for measuring length because everyone's foot is a different size.

### Standard Units and Young Children

Young children might understand that the words “weight,” “height,” and “volume” are associated with measuring. It will take a while to understand that in order to compare and contrast objects or to build to scale, everybody needs the same starting point.

To begin, consider explaining to your child why a standard unit of measurement is necessary. For example, your child likely understands that he or she has a name, as do relatives, friends, and pets. Their names help identify who they are and show that they are a person. When describing a person, using identifiers, such as "blue eyes," helps to specify the attributes of the person.

Objects also have a name. Further identification and description of the object can be achieved through measurement units. "The long table," for instance, may describe a table of some length, but it doesn't say how long the table actually is. "The five-foot table" is far more accurate. However, this is something that children will learn as they grow.

### A Nonstandard Measurement Experiment

You can use two objects at home to demonstrate this concept: a table and a book. Both you and your child can participate in this measurement experiment.

Holding your hand rigid, measure the length of the table in hand spans. How many of your hand spans does it take to cover the length of the table? How many of your child's hand spans? Now, measure the length of the book in hand spans.

Your child may notice that the number of hand spans required to measure the objects is different than the number of hand spans it took for you to measure the objects. This is because your hands are different sizes, so you are *not* using a standard unit of measurement.

For your child’s purposes, measuring length and height in paper clips or hand spans, or using pennies in a homemade balance scale, may work well, but these are nonstandard measurements.

### A Standard Measurement Experiment

Once your child understands that hand spans are nonstandard measurements, introduce the importance of a standard unit of measurement.

You might, for instance, show your child to a one-foot ruler. At first, don't worry about the vocabulary or smaller measurements on the ruler, just the concept that this stick measures "one foot." Tell them that people they know (grandparents, teachers, etc.) can use a stick just like it to measure things in the exact same way.

Let your child measure the table again. How many feet is it? Does it change when you measure it rather than your child? Explain that it doesn't matter who measures, everyone will get the same result.

Move around your home and measure similar objects, such as the television, sofa, or bed. Next, help your child measure their own height, yours, and each member of your family. These familiar objects will help put into perspective the relationship between the ruler and the length or height of objects.

Concepts like weight and volume can come later and are not quite as easy to introduce to young children. However, the ruler is a tangible object that can easily be transported and used to measure larger objects around you. Many kids even come to see it as a fun game.