You're right, "Je connais" is a better wording. But you will often hear "Je sais" in common conversation even if it's not the proper verb to use in that situation.

>Not trying to teach my grandmother to suck eggs, and assuming you're a francophone, as i understand it wouldn't it be "...Je connais simplement quelques expressions."?
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>Savoir is to know a fact, whereas connaitre is to know a thing: person, phrase, city, etc.
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>eg "je sais que tu parts demain" vs "je connais votre destination" ???