I think the correct verb for knowing (something) is cognosco, cognoscere, cognovi; I think with scio, you're expecting a whole clause (indirect statement, indirect question).
See Giuseppe's comment, below: Yes, there are indeed examples of sciō controlling a fact in the accusative (or something like nihil , nothing, or omnia , everything), although I think the longest set of examples in the OLD are for the indirect statements and indirect questions introduced by the verb. So, I withdraw my objection to "quīnque verba sciō" !
Actually, Lewis and Short's Dictionary has variuos examples of scio + accusative:
dispensator litteras scit, is omnes linguas scit, comoediam scire ...
And it defines cognosco as to know, but in tenses derived from the perfect, while the present usually means [t]o become thoroughly acquainted with (by the senses or mentally), to learn by inquiring ....
Other verbs are used this way in Latin, such as: memini (I remember, lit: I have recalled to my memory), odi (I hate - sorry I can't find a way to translate it in English!), consuevi (I am accustomed = I have become accustomed), see Allen and Greenough's New Latin Grammar §205.b and §476
This way of seeing a perfect tense as the present result of an action is common to other Indoeuropean languages: cf. Sanscrit veda or Greek οἶδα: I know (because I have seen - both have the same root of Latin video, English wit, German wissen...)