Schools in the US often use an eTLD, "effective top level domain", which, although they have multiple levels, they are used as though they were a TLD like .com. The eTLD for schools is k12.{state}.us.

So if they use a www subdomain for their website, you can have lots of dots. I like these domains though, because they are generally unspoofable. You know for sure it's a real school domain if you see it.

Mozilla maintains the de facto authoritative list of these domains in a document called the Public Suffix List. That document has a real effect on how the Internet treats those domains.