Final answer:
The learning theory based on Jean Piaget's work that suggests active knowledge building in children through firsthand experiences is constructivism.
Step-by-step explanation:
The learning theory derived from the work of Jean Piaget, which assumes that children actively build their knowledge from first-hand experiences in stimulating environments, is known as constructivism. This theory holds that cognitive development in children involves an active process of construction rather than absorbing information passively. Piaget's stages of cognitive development indicate that children move through distinct stages as they grow, with each stage characterized by a qualitative change in thinking and reasoning abilities.