a ruler
METERS!!!The unit of measurement you would use to measure the width of your classroom is meters.
Parsecs
Centimetre.
Millimetres
You could use either inches or centimeters to measure the width of a sheet of paper.
I would suggest centimeters but lots of people use inches.
15 m
a yard stick
ruler
meters
I would use meters.
You would likely use a ruler or a measuring tape.