After getting 'out' in a game because the rope got stuck in her leg while jumping, Aru says that the rope deliberately got her out. At what stage of Jean Piaget's theory of cognitive development do children reason like this?

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?