Könnt ihr schwimmen?
Is this a plural you, and is it formal or informal?
Das ist sehr interessant, was ihr schreibt! Ihr könnt die Verwendung dieses Pronomens üben, indem ihr oft selbst Sätze damit schreibt. Damit stärkt ihr euer Ausdrucksvermögen.
Ihr braucht euch nur vorzustellen, dass ihr die Menschen im Forum gleichzeitig ansprecht. Schon müsst ihr das Wort verwenden, das euch solche Mühe macht.
(Dies ist ein kleiner Übungstext speziell für sweilan und SlamRN :-))
One of the reasons it has been my weakness is that when I was in school learning German, it would be extremely rare that I would meet with more than one German speaking person. So I would always use Du or Sie. So it was embarrassing in Germany because I kept using Sie when speaking to a group of friends.
Euch is the dative and accusative pronoun 2nd pers. plural, like "you all". The formal version would be sich, which is actually 3rd person.
- Peter, setz dich bitte. (sg, informal)
- Herr Müller, bitte setzen Sie sich. (sg., formal)
- Jungs, setzt euch (bitte). (pl., informal)
- Liebe Kollegen, bitte setzen Sie sich. (pl. formal)
Talking about 1st, 2nd and 3rd person can be confusing when we use the 3rd person plural to address somebody who is actually 2nd person singular, but we want to be polite ;-).
"Ihr" is second-person plural, used when speaking to a group of people. It's less formal than "Sie" but not as informal as "du". When I was in university, professors would normally address the class as "Sie", which is the formal form of address for both single people and groups of people, but occasionally they would address us as "ihr" to make it clear that they were speaking to us collectively as a group and not to one single person, while they would never say "du" to an individual student. Also, don't confuse "ihr" in this context with the possessive word "ihr" (which means both "her" and their") as well as "Ihr" (which means "your" when speaking to someone whom you say "Sie" with).
What you describe is correct, however, it applies only to a very specific set of situations. The "professor/student" relationship you describe is the only one that looks convincing to me. There may be colleagues in a company who address each other with "Sie", but refer to a group as "ihr"; this seems possible to me, too.
The decisive points for these special situations are:
1) There must be a certain degree of acquaintance among all the participants.
2) This form of address works only unilaterally. The professor may address a group of his or her students with "ihr", while this would not be possible if a student addressed several professors simultaneously.
3) This shows that there is an issue of age/hierarchy. The older person / the person higher in the hierarchy may use this form of address, but not vice versa.
Therefore, for learners of German, I think it is safe to stay with the equation "ihr" = "plural "du"" for their own active communication. They should only be prepared to encounter a situation as described by you.
I think there's a very small grey area where you could use "ihr" (for a group) when you wouldn't say "du" (to the single person) without sounding rude - but since the question of rudeness is for that person to decide, and - I think - also very much a matter of "traditional usage in a certain subculture" that a person could think of as e.g. outdated, it's easy to come off as rude, so I'm very careful with it.
However, sometimes I'm in a situation where I think I could call somebody "du", e.g. because I'm (although a stranger) in an environment where people use "du" with each other, like when the local football club puts up a stand at the Christmas market to sell sausages, and I can see they're in an "informal" mood. I wouldn't dare to address one of them with "du", because I'm still a stranger; maybe I'd think that "Sie" would come off as a bit formal, but I can settle for "ihr", referring to the group as a whole: "Habt ihr auch Steaks?" ("Do you also have/sell steaks?"), "Ihr verdient heute bestimmt viel Geld" ("I'm sure you're earning a lot of money today"). But I've got to be sure they won't think it's disrespectful; you definitely shouldn't walk up to a group of musicians playing on the street and address them with "ihr".