"The bears are called Hans and Karl."
Translation:Die Bären heißen Hans und Karl.
I wrote: 'Die Bären sind Hans und Karl' because Duolingo accepts "Ich bin Julia" and "Ich heiße Julia" as being equivalent. I do understand that "heißen" means "to be called" and that "sein" means "to be". Is there a reason why in one case Duolingo accepts both and in the other only one?
The reason is that "Die Bären sind Hans und Karl" is not correct German. ;) You are right, there's no real difference between "Ich bin Julia" and "Ich heiße Julia". You can also say "Das sind Hans und Karl" when introducing them to someone else, but "Die Bären sind Hans und Karl" just doesn't work. I wish I could give you a better explanation, but I'm afraid it's just one of the many quirks you have to get used to when learning a new language.
But the two verbs
aren't actually the same. Yes, you could introduce yourself either way--but sein does not mean "to be called" and heißen does not mean "to be". Duo is a computer program, and it cannot read. All it can do is compare user responses with the correct responses in its database, and it does not regard those as interchangeable. In translation items, we have to translate the words given in the sentence, and not inject words from a different sentence expressing roughly the same concept.
Scharfes s is not an umlaut – that's the two dots over a letter. ß is the same as ss and if you can't type the letter, you can use double s instead!
As for the question, I'm not sure I fully understand, but yes, absolutely, the article and noun are treated as one part. Surely you can't imagine something like "die heißen Bären". There have been so many sentences in exercises up to this point!
This has already been answered several times above, but here it is again. You
do have umlauts, actually. On either iOS phones, iPad, or Android, a “long touch” (touch and hold) on any of the vowels will bring up all the variants of it, including ä, ö, ü. Doing the same on the “s” will produce variants of s, including ß. Just select the one you want.
If you’re using a Windows desktop computer, you just click which character you want from the screen, where Duo gives them to you to pick from. Also, you can use Alt codes (Alt-0223) or Character Map from the system tools.
Actually, you do have access to it; don't use a capital B -- that's incorrect as it isn't a B at all, it's a double-S. You have several solutions.
1) If you're using a mobile phone or iPad, just do a long touch on the 's' letter, and the variants of it will appear so that you can select the ß ("ess-tsett").
2) On a Windows desktop computer, press Alt and while holding it, type 0223 from the number pad (Alt-0223).
3) Easiest of all, the German characters are on little buttons on the Duolingo screen, right below the text entering window. Just click the one you want.
4) if all else fails, type "ss" instead. Duo might call it a typo, but it usually accepts 'ss' in place of ß.
Yes, that happens. Remember that it's a computer, and not a live person who can read, so it doesn't know what you meant. The software just compares the correct answer(s) in its database with the answers that people enter; either the answers match, or not. If they don't match (for any reason), the software marks them as incorrect.
Also, “bear” in mind, all names and all nouns in German must be capitalized to be correct.