Informal Units of Measurement

A former colleague of mine once commented that it is a waste of time to have students develop their own units of measurement with older kids (grades 5-8ish).  I disagreed then, and I disagree now.  Informal units of measurement (especially in the upper Elementary grades) have a number of practical benefits:

  • They make it easier to focus directly in the attribute being measured, and in turn, what is means to measure

  • They give a historical content for mathematics that helps them see how and why mathematical concepts have developed as they have

  • It gives a rational for the importance of standard units, rather than the teacher just telling them they are important, they get to see for themselves why

  • It is fun, and more importantly, when developing your own informal unit, you have to think outside of the box and focus on the concept and big idea of the attribute you are measuring (creative problem solving)

  • We use them everyday in our lives (a pinch of salt, a splash of hot sauce, a handful of counting beads, a bit of tape)

  • There are more, but my brain is not working properly.  Please add more in the comments below!

My students came up with some wonderful ideas to kick of their inquiry into measurable attributes.  To frame it, our four main categories of measurable attributes are Time, Volume, Area, Weight, Length (this includes depth, height, etc).  We are each doing an inquiry into each one and will present our findings to the class at the end of our inquiry (and each group will plan a series of lessons for the rest of the class to help them get their concept).  Here is what they came up with:


What I want to measure: The time it takes to run a lap of the track

How I will measure it: Sing Happy Birthday and count the number of Happy Birthdays it takes

Answer: 20


What I want to measure: The volume of a cup

How I will measure it: How many spoonfuls of water it takes to fill the cup

Answer: 28


What I want to measure: The length of a table

How I will measure it: How many toothpicks I can lay across the table

Answer: 27


What I want to measure: The area of the carpet

How I will measure it: How many pillows will cover the carpet

Answer: 33


What I want to measure: The weight of a dictionary

How I will measure it: How many paperback books equals one dictionary

Answer: 12 (but that will change if the thing in the middle is skinny or fat)


  1. Marcie Lewis1.12.11

    I think the importance of using informal measurements is that it meets students where they are. They see objects, hear sounds, pick up objects on a regular basis but they don't always naturally consider how they compare to each other beyond the surface of bigger, heavier, longer, etc.. The ability to compare and contrast objects is an important skill that deserves time to explore.


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