Final answer:
By early adolescence, cliques become mixed and this forms the basis for dating, with social expectations around romantic relationships becoming more pronounced in high school.
Step-by-step explanation:
By early adolescence, cliques become mixed and form the basis for dating. During middle childhood, children typically play in same-gender groups but begin to form mixed-gender groups as they enter pre-adolescence and, subsequently, adolescence. This progression leads to the development of significant relationships outside of peer circles, and by early adolescence, it becomes more common and socially expected for young people to start exploring romantic relationships. In high school, the importance of dating and being a significant other becomes more pronounced as students absorb the social expectations that come with the high school experience.