## Wednesday, October 26, 2016

### Measurements

Did you realize that looking at measurement is the perfect time to introduce a bit of a history lesson so there is a cross curricular connection?

Just think about where the first measurements came from?  One of the earliest is the Cubit which is the length from the tip of the finger to the elbow.  Hmmm, everyone could measure their bodies to find out how much the cubit varies within the classroom.  It wouldn't take much to start a discussion on what problems these differences might make.

A cubit could be subdivided into the foot or hand.  The hand is set at 4 inches and is the standard measurement for the height of a horse so if you horse is 15 hands high, it is actually 60 inches tall or 5 feet.  A nice exercise built to create fluency for converting between systems of measurement.

The yard has existed for a long time but it was standardized during the reign of Edward I when it was determined that 3 feet = 1 yard or Ulna.  In addition, the foot was declared to be one inch but the inch was based on the length of 3 barley dry barley corns.

It was at this time, other measures were standardized such as five and a half Ulna equal a perch also known as a rod.  An acre was declared to be 40 perch by 4 perch.  Wow, think of the fun one could have figuring out the number of feet in that acre and comparing it to the current definition of an acre!

Interesting fact - the perch was originally defined as the total length of the left foot of the first 16 men leaving church on Sunday.  That would make a cool exercise in class to see how it would work with modern man.

Another interesting fact - many of the standard measures for meters and yards were made of metal but depending on the type of metal, the official standard could possibly shrink by 1 part per million every 20 years.

Beginning in the 1500's or so, countries began working on standardizing all measurements so there was a consistency of use.  France was one of the first countries to work on standardizing measures because there were over 250,000 different units of measurement being used.  That could be so confusing.  They defined the meter as one ten-millionth of the distance from the north pole to the equator.

Eventually after several years, the official length was made and the rods to represent the official meter were made out of plutonium.  The United States claims a foot is 0.3048 of a meter which sort of makes sense since a meter is about 3 1/4 feet.

I love the idea of asking my students "Why is it important to have standardized measurements?" I can hardly wait to see their answers.  I'll let you know some of the responses.

I'd love to hear what you think.