preoperational, concrete operational
The classic conservation task developed by Piaget involves two short containers that contain equal amounts of liquid. While a child watches, the water from one container is poured into a tall, thin beaker, and the child is asked which beaker holds more water, the short container or the tall container. Four-year-old Daniel answers the question incorrectly, while seven-year-old Emily is able to answer the question correctly. Daniel is in the ____________stage of development, whereas Emily is in the ___________stage.