Back when I was teaching grade school, the "salad bowl" concept had replaced the melting pot as metaphor for our multicultural society. So, during the holiday season, I had my elementary students grate potatoes and onions for the latkes that we ate together in the classroom when learning about Hanukkah. We sat around a lighted luminary as I read to them "The Farolitos of Christmas," and we learned the meaning of the seven Swahili words for the seven days of Kwanzaa, as well as the values for which they stand.
We sang a patriotic song every day after the pledge of allegiance, including "Lift Every Voice" as one of the choices. (Their favorite was George M. Cohen's "You're a Grand Old Flag"!)
We never prayed in the classroom, unless someone used the moment of silence we took to "center" ourselves for the work of the day.
I believe in the separation of church and state. But I also believe that we are a rich and diverse culture, and the elementary classroom is the perfect place to learn about it.