According to Jean Piaget, in the formal operational stage children begin to use abstract thinking processes.
Abstract thinking is one that occurs through purely mental processes and first appears in early adolescence, approximately according to the psychologist Jean Piaget.
Piaget called it "formal thinking" because it occurs in the stage of "formal operations", which occurs between 12 and 16 years of age.
About abstract thinking processes:
Therefore, we can conclude that according to Jean Piaget, in the formal operational stage children begin to use abstract thinking processes.
Learn more here: https://brainly.com/question/24716439