Final answer:
Kyle choosing to play with Justin is an instance of gender segregation, an outcome of gender socialization influenced by societal norms. This can lead to gendered patterns in social interactions during early childhood.
Step-by-step explanation:
On the first day of preschool, when Kyle chooses to play with Justin instead of Julia, this is an example of gender segregation. This choice may be influenced by gender socialization, where children learn to interact with the same gender based on societal norms and stereotypes. Although preschoolers are making choices, these choices are often shaped by the messages they receive from society about what is deemed appropriate for boys and girls. The Egalia preschool in Sweden's experiment with a genderless environment represents one attempt to address and minimize such gendered patterns of behavior and interaction among young children.