Measurement is an important part of everyday life, but kids don’t automatically understand that even though there are different ways to measure things, there needs to be a standard unit of measurement by which to do it.
A standard unit of measurement is one which everybody can use as a reference point to describe different objects, such as inches/centimeters or pounds/kilograms. Your child may understand that the words “weight,” “height,” and “length” are associated with measuring, but it will take awhile before he understands that in order to compare and contrast objects or to build to scale, everybody needs the same starting point.
For your child’s purposes, measuring length and height in paper clips or handprints or using a pennies as weight in a homemade balance scale may work well, but these are nonstandard measurements.
That is, they are not a reference point that the rest of the world can work with because hands are different sizes and even pennies differ a little in weight. Once your child is more familiar with how measurement works and is interested in measuring things, you can introduce him to the vocabulary people use for standard units of measurement.
How much do you know about measurement? Take the Units of Measurement Quiz!