Anytime anything is the least bit controversial, someone comes up with the idea to ban it. Instead of banning Halloween parties in schools, why don't schools do what they are supposed to do, and educate children?
Even if you yourself do not believe in a holiday, there is no shame in learning about the culture or peoples that do. For Halloween, there is enough rich history there to turn what may have just been a party, and what might have become just another school day, into a rich lesson-plan full of beliefs and cultural celebrations throughout time. Children of different backgrounds can explain what they do for holidays, or what they don't do, and why. Thus children can learn not only from lesson plans, but from eachother.
It shouldn't be limited to Halloween, either. Christmas, Easter, every holiday can be treated the same. But the basis for this argument comes not only from a learning standpoint, but also from the belief that children need to have a little fun. Everything children ever enjoyed about school is slowly being taken away- recess, because either there's not enough time, or the area is unsafe for children to be outside in, art and music are gone first anytime a school has to reduce its budget, and now holidays are suffering. If a parent or student is insistent about not participating in a celebration, they can be given another assignment and taken to another room- which is exactly what they did when I was in school. It would be explained to us that they had left because their faith or culture did not believe or otherwise didn't celebrate the holiday, and our activities would otherwise go on as normal. Not once do I recall anything ever being said or done to these children that was inappropriate afterwards, except that children are naturally curious and might ask a few questions about it afterwards.
Learning about other cultures and faiths facilitates understanding, not the other way around. Halloween, as with many holidays in the United States, has become more of a commercial holiday than anything else, and that is the real sadness of the situation. Yet, instead of using the opportunity to explain the relevance and background to the celebrations, many would rather just ban them altogether. Banning holiday parties and celebrations takes away from the learning experience and helps to facilitate ignorance.
Halloween has ties to ancient calendars, Dia De Los Muertos, All Saints Day, and the natural changes of the season. As the world grew chilly and trees lost their leaves, many cultures believed that this was a form of "death" for the earth, before it went into winter hibernation and was born anew. Many of them believed that the spirits of their ancestors were closest this time of year, and possibly the spirits of other dead or demons as well, and thus dressed up in costumes to "confuse" the spirits. With this short explanation alone, I can see lessons on Mexican heritage, the history of Halloween traditions, plans about Autumn and nature, and possibly the chance to explore the child's own family tree and learn a little bit about their own ancestors. When properly explained, learning about holidays does not violate any individual's rights, regardless of their beliefs or culture. It is also something that can be fun and enjoyable- and children love a celebration for any reason.
Part of being a child is having fun and learning new things. If we take away the fun part, which almost seems to be what we are trying to do, we are doing no favor to children. In fact, we are probably stifling their natural creativity and curiosity. Instead, let's learn to use it to help educate children, and stop this silly talk of banning every little thing that comes up a little on the "possibly offensive" side.