Final Answer:
The nurse determines that the toddler's behavior of smiling, waving arms and legs, and vocalizing when he sees his mother setting up the high chair for lunch is indicative of progress in Piaget's Sensorimotor Stage of cognitive development.
Step-by-step explanation:
Jean Piaget's stages of cognitive development include the Sensorimotor Stage, typically occurring from birth to around 2 years old. In this stage, infants and toddlers learn about the world through their senses and motor activities. The described behavior of the toddler, such as smiling, waving arms and legs, and vocalizing in response to the mother setting up the high chair, aligns with the development of object permanence and the understanding that objects (like the high chair) continue to exist even when out of sight. This behavior indicates cognitive progress, as the toddler demonstrates an awareness and anticipation of familiar routines and objects.