A child has developed the ability to sort objects on the basis of their physical properties. The child can also perform complex operations on problems as long as the issues are concrete and not abstract. According to Jean Piaget's theory of Cognitive Development, the child is at which stage?

According to Jean Piaget, mathematical knowledge is primarily acquired through:

How does Piaget's theory explain children's process of learning mathematical concepts?

A Class 2 teacher notices that when she pours water from a short, wide glass into a tall, thin one, her students insist that the taller glass holds more water. Based on Piaget's theory, which stage of cognitive development are these students most likely in, and what concept are they struggling with?