Current wisdom suggests the two words can/may be used interchangeably, but "may" is considered a little more polite making it more appropriate for formal situations.
Is there a difference between "May I" (do I have permission) and "Can I" (am I able) in Spanish?
I don't think so, i.e. puedo can mean both, although it would make little sense to ask someone else of what you are able to do IMHO.. anyways, it will always be clear from the context
"Can" is not correct. "May" is correct here, yet not accepted. Reported 3/1/18
"Can I" is good here. It's what people usually/often say. It may not be perfect English but if the point is to learn Spanish then it's important primarily to understand the sentiment being conveyed by the spanish sentence, no?
What I mean is if someone comes up to you and says "puedo llevar tu bolsa" it's more important to know what they're asking than to get bogged down worrying about whether they are saying 'can I' or 'may I'.
That's the way I think about it anyway; it helps me worry less about Duolingo's sometimes questionable English grammar.
There's absolutely nothing wrong with using "may," which is what I was taught should be used to ask permission. However, that usage is neither universal nor intrinsic to the definition of either "can" or "may" (cf. Oxford online dictionary.)
Regardless of one's personal opinion regarding proper English usage, Spanish makes no such distinction and that should be enough for Duo to accept either "can" or "may."
What is wrong with " can I take away your bag?" I was at a Latino restaurant just last night, and that's what I was asked.