Way back in the last millennium, when I was in a public elementary school in northern New Jersey (approximately 1974-1980), our school had holiday-themed classroom activities and music performances that were mostly secular. Snowmen and sleigh rides and reindeer featured heavily, and for every song or activity that made explicit mention of Christmas, there would be one that made explicit mention of Hanukkah (you know, for balance). It was pretty clear to us students, though, that serious effort was being made to keep holiday-themed stuff at our elementary school as secular as possible ... because that's what was appropriate in a public school (where kids had to be there whether or not they worshipped in a particular way, or at all).
More recently (approximately 2004-present), I have been the parent of students in a public elementary school in northern California where the holiday-themed classroom activities and music performances have been decidedly less secular. There has been an overabundance of straightforward Christmas carols (complete with verses with religious content), weak attempts to recognize the existence of Hanukkah by singing that one dreidel song, and no apparent effort to recognize the existence of (let alone incorporate in activities, performances, or celebrations) the seasonal celebrations of other religious traditions (e.g., Diwali). And, this convergence of "winter holidays" towards Christmas in the public elementary school has been happening despite a significant population of kids in the classroom who are not Christian, nor Jewish, nor Muslim.
All this leaves me wondering: Were serious efforts to keep religion from encroaching on our public school activities an East Coast Thing? Were they a late 20th Century thing? How is it that the adults running things in a significantly less diverse school district some 40 years ago were better at acknowledging that their student population might not all believe the same thing or partake of the same religious or cultural traditions than are the adults running things in our wildly diverse school district here in California?
Honestly, it's all pretty weird, and I'd like to understand the source of this receding commitment to secularism better.