I say no
I may be a student, but that doesn't mean my opinion isn't true. These blocks are often pointless. For example, let's just say I finish all my work on a period I work at a computer, and the teacher doesn't have any new work posted yet. In such a situation, I should be allowed to go on any site I want, within reason. Now, some blocks are acceptable, mainly against pornographic websites, but blocking things educational or entertainment based is just not right. Firstly, most people on a computer in a classroom have either finished their work, or are in a class they WANT to be in, due to the subject, meaning they are going to get their work done, most likely. Very rarely do classes not based on the use of a computer go and use them. Second, people will just find ways around these blocks anyways. For example, going to a wiki site, or using their phone. Most providers nowadays even provide data connection, allowing them to get past the blocks because they aren't using school internet. Third, most of the sites blocked are in one of three categories. They all seem to either be game sites, music sites, or even sites that even have information about games. For example, I just tried to go on a D&D wiki to find a sheet to homebrew a class. I cant though, because the good one is blocked. The other, maybe, five percent of blocks, are fine, things like Pornhub and junk. Fourth, there are several sites that can't be blocked. Namely Weebly sites and Wikia sites. If somebody wanted, they could just put a bunch of porn or games on a Weebly site, and manage to get past the school blocks because if they blocked Wikia or Weebly, they would be blocking important tools for every subject. Fifth, it mutes this so-called freedom of speech we Americans have, by allowing the small amount of people at a school to block whatever the heck they feel is inappropriate. In other words, anything that disagrees with their ideals, religion, etcetera. The whole idea is just a failure.