Care and Feeding Photo illustration by Slate. Photo by Stella_E/iStock/Getty Images Plus.  Care and Feeding is Slate’s parenting advice column.  Have a question for Care and Feeding?  Submit it here . Dear Care and Feeding, Our 5-year-old is struggling in his mixed-age classroom because it seems that during unstructured play time, the girls seem to huddle around and play, while the boys (led by the oldest boy in the class) run around, play cops and robbers, tackle each other, etc. My son comes home and says he wishes he had friends at this school like he did at his old school. When I encourage him to play with/talk to other kids, he says, “But I don’t like to play like that, so they said they don’t want to play with me, and the girls told me we are each other’s best friends, and they always huddle together and talk in the corner.” The teacher says that he doesn’t mix with the other kids and stays on the sidelines. According to the teacher, he seems happy to be alone and sings by himself.…