If you were measuring the whole of the classroom, you would most likely measure area, that is, of the floor space, or volume, that is, of the entire room. Therefore, you would be unlikely to measure simply the length of one side of the room.
meters
gr
The meter.
Meters or yards if it's the school library, in the same building or on the same campus as the classroom. Kilometers or miles if it's simply the municipal library, in the same city as the classroom.
METERS!!!The unit of measurement you would use to measure the width of your classroom is meters.
in feet
meters
The metric unit of the meter would be the appropriate measure of the area of classroom. Calculating area involves multiplying the length (in meters) of the classroom's length and width. Area of the classroom would be in square (^2) meters.
Meter stickI'm thinking you would use a tape measure
With a tape measure or a yard stick.
yards
A stapler
Meters
Identify the SI until you would use the measured the width of your classroom
I would use a tape measure. This would require one person to help me, since the tape measure would have to be held at both ends. Even if the classroom is longer than the tape measure, I could just mark the full extent of the tape and then measure again from there.
The square meter.