I’m taking a class through E-Learning for Educators (Alabama) on measurement.  Here are some thoughts from today’s readings.  They are in no particular order.

Students need to develop a concept of measurement that includes the idea that measuring requires consistent units. An inch is an inch is an inch, but an inch isn’t the same as a centimeter–they can’t (practically) be combined when measuring the length of something.

Geometry (“Earth measure”) has its roots in spatial measurement.  It helps develop an understanding of 2- and 3-dimensional space. 

Measurement links math with the world, especially with science.

The idea of a unit of measure is fundamental, as is the notion that measurement involves the organized accumulation of standard units.  http://books.nap.edu/openbook.php?record_id=9822&page=281#

Developing the student’s ability to select an appropriate unit is critical.  This is not simple a matter of using inches vs. feet when measuring a paperback book; it involves developing an understanding of the units of length, area, and volume as well as well. 

Subdividing a space according to a unit and counting those units is called iteration.

Young children tend to think of a measurement as a position on a ruler, rather than as a measure of the space between the beginning of the ruler and that position. This can lead to trouble when they are measuring a length that begins at a point other than “0” on a ruler. It is notoriously difficult for students to correctly measure a line that extends from 2 to 5 on a ruler. Many say 5; others count the inch markings and say 4.  http://edtechleaders.org/documents/elemmeasure/Reading_Units.pdf

The idea of reciprocity refers to the fact that larger units require fewer units to measure a specific aspect.  A particular distance might be 1 yard or 3 feet or 36 inches.