This week in math we started unit 3: measurement.  We learned how to use referents and instruments to measure the world around us.  Something that I had never used before was a micrometer.  A micrometer is a gauge that measures small distances or thicknesses between its two faces, one of which can be moved away from or toward the other by turning a screw.

Learning how to use a micrometer was cool because it basically tells you the decimal points because it has a rotating collar that lines up with the number line / ruler part for the whole numbers. The number that lines up with the number line is the decimal place.  For example if something was 12.20 mm the collar would be parallel to the 12 and the number on the collar would be 20.


The reading on the micrometer would be 3.1 cm.