日語 Japanese Ask Questions Thread2 質問

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Japanese - Ask questions thread
http://dis.4chan.org/read/lang/1174719097/l50

Maybe I'm a bit (or, more likely, very) confused, but somewhere I got the idea that adding かなあ to your sentences means something "I guess" and そうかなあ means "I think so". But I'm not sure if this is correct and how to use it, in what context, so I tried several sources to find out its use and I can't find any evidence of this even existing.
Huh?
Help, anybody?