An experimenter lines up pairs of checkers into two identical rows. Then the experimenter elongated one of the rows by spacing the checkers farther apart. This is a classic test of.

The correct answer is conservation of number

According to Piaget's theory, when the child has no notion of conservation, that is, when he does not believe that there may be different configurations for the same object, he is going through the preoperative period or early childhood, which occurs from 2 (two) at 7 (seven) years.

answer; regard the action of other people negatively;

because the early people found out about it.