Translation:We have a little black dog.
Here's another inconsistency in this course. In this question 小 means little, but if you use 'little' as the interpretation of 小 instead of 'small' in other questions, you get marked wrong.
There's another question with the answer: "I have a small nose", but if you reply "I have a little nose" you get marked wrong.
This just causes unnecessary confusion.
But this is a Chinese lesson, not an English lesson, and there are many people who take this course who aren't native English speakers because Chinese learning materials aren't as available in their first language. I think Duolingo should be more lenient about advanced English grammar points like this - surely someone who types 'black little dog' has understood the meaning of the Chinese sentence!
The syntax is the same in each language, therefore, 黑色小狗, black little dog, should be considered a correct translation. However, I would like to detract for a moment from showing(off), what a smart(ass?), I am, to give hearty praise to the devs for a superb job, and all the times I don't have issues with translations. Thankyou, sincerely, and keep up the good work!
Such things, in fact, put people off Duolingo. I just want to learn some Chinese and took the course in English because - guess what - there are no courses in other languages including my mother tongue.
Indeed, the grammar and the word order rules are important, but there should be some space left fot the lexical variation! We don't have any actual context here. We don't know whether it's a little dog (why not small by the way?) or a puppy. Please, please correct that!
I'm not an expert, but sources suggest that the general rule which is true in most but not all cases is that one syllable adjectives are not followed by a 的, but multi-syllable adjectives usually do have a 的 on the end. Colour names are usually multi-syllabic, so these are often followed by a 的. 小 is only one syllable, so it usually isn't followed by 的, plus 小狗 (without the 的) is the typical Chinese name for a puppy or small dog.