Translation:My wife, I met her at a campground.
This far up the tree we should all know perfectly well how to say "I met my wife at a campground" by now. The point of the English isn't to always be a perfectly natural thing you would say, it's to show that you understand what you're being taught, which in this case is a particular grammar point. You probably won't use this exact sentence because it's very contrived, but you will need to use the agreement it's teaching if you want to construct more complex written sentences.
I fail to see how translating it naturally wouldn't "show that you understand what you're being taught". We simply don't speak like this in English. It doesn't make any sense to try to wedge the grammar structures of French into another language where they don't fit.
Yes everybody should know how to say "I met my wife at a campgroup" by now. This lesson teaches another way to say it that is more emphatic: "Ma femme, je j'ai rencontrée dans un camping". None of that necessitates butchering English.
Remember the suggested answer has to work in the other direction as well. Duo doesn't have separate sentences for English->French vs French->English. How would you suggest they teach gender agreement for avoir verbs if the most obvious translation for the English removes that construction from the sentence?
I, and I am sure a lot of other people, started doing Duo because I wanted to learn a language enough to be able to grasp news reports, etc., and communicate with locals when visiting a country. I did not join to learn the minutiae of grammar - nor was it advertised as 'a grammar practice tool' when I joined. If that is what it is now trying to do (teach to possibly degree level) then I think it ought to split itself into teaching at a more basic level, and then at a higher level, so that people can choose what they want to achieve.
Sorry, this is a reply to the following post from captaingarbonza, as 'reply' if not an option!
You cannot know if the higher levels of the tree are useful or not until you try them. Also you have to take level one on them to get to the next subject, so you cannot always avoid them.
In my opinion "grammar practice tool" is not a very fair description nor a very accurate depiction of Duolingo.
To me, Duo's strength is as a vocabulary builder, but it doesn't just teach you words, it teaches you how to use those words and how to fit them together with each other to build useful sentences.
I think that you will find, if you give it time, that this fits well with your stated aims.
But Duo is pointedly not trying to teach you grammar. It does require grammatically correct responses, sure, as I think it should.
But it expects you to absorb that grammar through repetition and through learning from your mistakes, the way that a baby does.
It is left totally up to you whether you try to augment that by researching the grammar theory behind it.
I came into this course with a strong understanding of the grammar behind a couple of other languages, so I have naturally gravitated in that direction, and I would guess from his other posts that captaingarbonza is also of that persuasion, but lots of others prefer not to.
It shows me at the top of the page that the focus of this exercise is "l'ai" and it doesn't take a genius to figure out that the requirement is to match it with "rencontrée".
Naturally, on an FR→EN page like this one that is only really relevant to the "Type what you hear exercise", and possibly a "type the missing word" exercise.
It is distinctly possible that the highlighting is tailored to your personal profile and the skills and vocabulary which you have previously covered, so your experience may differ. I am not sure whether it follows that tracking through to the forum pages.