Hi!

So I’m going through season three lesson 8 and it gives examples of negative verbs. One of the examples is:

それ　は　しりません

Which is translated to “I don’t know that.” Isn’t それ the direct object? If it is, why doesn’t it take the particle を instead of は? I get that you’re supposed to infer that it’s not the thing that’s doing the knowing, but I just thought it seemed like a strange way to write it. Thanks for the help!