A surveyor's wheel (see link).
A pedometer is also an option.
A tape measure would be the tool, measuring in centimetres or inches.
We use perimeter to measure the length and breadth so that we can easily find out the measurement of a figure
area and perimeter.
Yes on vast scale
Metre.
I would use kilometers.
use your ruler to measure the sides
A ruler should be used to measure it. Once you have the perimeter, it would probably be most convenient to express it in terms of either inches or centimeters.
units with perimeter square units with area
i would use feet or inches depending on the size
I would use a ruler or a tape measure. After I was done, I would express the measurement in centimeters or inches.
Use whatever is appropriate, or whichever you prefer. Centimeters are appropriate more often.