If testing shows an element is a poor conductor of electricity, it is probably a(n)

An electrical insulator.
Insulator is something opposite to conductor, electricity cannot transfer through it easily. Therefore we can say a poor conductor is also a good insulator.
Examples of electrical insulators include plastic, wood, cloth etc. Because they are lack of free electrons that cannot transfer electricity fast enough.

Engineers have contribute to society in many ways like making the technology we use today or any type of power energy material