According to the Swiss Biologist -- Jean Piaget on the cognitive development in children, he touched and explained four basic stages of cognitive development in children and one out of the four stages is known as the formal operational stage. The other three are; concrete stage, sensorimotor stage and the preoperational stage.
I will explain the formal operational stage Since it is the only one out of the four that deals with this question. The formal operational stage can be said to be the last cognitive development stage in children which usually start at the Age of 11. It is the stage where; '' ...can use abstract thinking to problem solve, look at alternative solutions, and test these solutions."
