Permissibility of boys wearing ties to school

Assalamu Alykum. I humbly request the fatwa on muslim school boys wearing neck ties to school. I am under the impression that it is ok providing that it is not silk ties, but would just like some more clarification. The school is obviously not an Islamic School and they have their rules and regulations, should we abide by these rules as we opted to send our children to a non-Islamic School?