Answer:
When making experimental measurements, the instrument we use is important, because different tools have different degrees of accuracy. Therefore, it is necessary to find the instrument that best meets the required accuracy needs of the measures that we want to get.
Using the right units is a useful thing because it can make the task of understanding measurements easier. For example, it would be a bad idea to use kilometers to measure the dimensions of a book, because we could loose accuracy and it will not be easy to interpret.
But if we use centimeters or inches, the measurements of that book will be easier to interpret, and much more accurate.
