Lesson 4: Referents - Common SI and Imperial Linear Referents

   Constructing Knowledge

Linear referents are used to estimate the length of an object when an exact measurement is not needed or a measuring device is not available. Both the SI and imperial systems of measurement have some common linear referents.

Common SI Referents
SI unit of measure Common Referents
millimetre thickness of a dime, thickness of 10 sheets of paper
centimetre width of a pinky finger
decimetre length of a whiteboard marker or pen
metre length of a baseball bat, 1 adult stride length


Common Imperial Referents
Imperial unit of measure Common Referents
inch width of a thumb, diameter of a quarter
foot length of a binder, length of a sheet of paper
yard 1 adult stride length


Referents for the larger units of measurement (mile or kilometer) have not been given here because they are too large to be used in a practical way to estimate lengths of common objects. Within the scope of this course, the focus is to use referents of common objects to measure short distances.


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