We have Microsoft Family Safety turned on on the computer DS uses, which is really just because it was as easy to do as not on the new computer, but mostly rely on DS's sense, as Madoosa says. Combine with making sure he understands I'm his sysadmin and you don't keep secrets from the sysadmins :-) It's not actually that easy to find inappropriate things by accident, unless you have very strict ideas of what's inappropriate.

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