Why would it be difficult to experimentally calculate the speed of sound in the classroom with a stopwatch and meter stick?

Sound travels quite fast and sound wave must pass through a medium, such as air.

To measure a sound in classroom you will require to measure the time it takes a sound to travel a measured distance using stopwatch and meter stick but it would be difficult because walls of classroom will create echos echos.

Echos are reflections of sounds which causes timing errors and make difficult to meausre the speed of sound.

as a general rule, scissors have blades less than 6 in (15 cm) long and usually have handles with finger holes of the same size. shears have blades scissors used to cut hair or fabric must be much sharper

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it