They would use a rain gauge.
Centimeters
meter
A scientist would most likely use a ruler or caliper to measure the length of a nail or other small object. These tools provide accurate measurements in centimeters or inches.
meter
Mm
the Newton
A Scientist would use a balance, either triple-beam or electronic.
You would use a graduated cylinder
This unit is the kilogram (kg).
length
A scientist would typically use a ruler or measuring tape to measure the length of a fish. They would place the measuring tool along the fish from the tip of its mouth to the end of its tail to get an accurate measurement.
to measure