Different periods in human history are named for the materials used to make tools. Dr. Franklin is searching through layers of soil, looking for tools made by humans. After screening the top layer of soil, he uses a magnet to help speed up the search.

Why would southern delegates to the constitutional convention have opposed the three-fifths compromise? a) they feared that the president would eventually become "king" in the united states. b) they believed it would be insufficient in protecting the united states from invasion. c) they opposed the creation of a congress that would give states an equal number of senators. d) they wanted their full population of slaves to be counted for purposed of congressional representation.