Question

what is the measure of the number of unit squares needed to cover a flat surface - area or perimeter?

Answer 1

area. Hope this helps :)

Answer 2

Perimeter is used to find the total length. And its units are not in squares.

Areas are used to measure the number of unit squares needed to cover a flat surface. And its unit is in squares, for e.g. meter square, cm square etc .

So out of the two given options, area is used to measure the square units covered by the flat surface .