Xavier studies a unit of world history until he believes he knows it well. he then goes over it several more times. he is using the study skill called

Xavier studies a unit of world history until he believes he knows it well. He then goes over it several more times. He is using the study skill called overlearning.

Explanation:

Overlearning means to practice newly acquired skills beyond the point of initial mastery. The term is also often used to refer to the pedagogical theory that this form of practice leads to automaticity or other beneficial consequences.

answer; acquired mainly during early childhood;