Translation:Other sports are also interesting.
08/04/18. "Other sports also are interesting" is now accepted as an alternate correct answer. Thanks for listening Duolingo!
"Hi wordwing, You suggested 'Other sports also are interesting' as a translation for 'Otros deportes también son interesantes.' We now accept this translation. :) Thanks for the contribution, please keep it up! - Duolingo [07/31/18]"
When possible, the try to make the sentences have a similar structure. También can often be translated as too, but that would mean moving it to the end of the sentence. Keeping a parallel construction is important for new learners. At least, that's what I think they were thinking ;)
Your sentence and the Duo sentence are both valid. Adverb (también) placement is flexible in Spanish.
An adverb usually comes after the verb it modifies.
In Spanish, the adverb can go at the beginning or end of the sentence, or immediately AFTER the verb or BEFORE it for emphasis.
I wrote the also at the end of the sentence and it was also accepted. In my native language German the word order would be like in the English sentence Duolingo gives, but for an unknown reason for me it does sound better when I put the also in the end. But because I did not read that someone wrote same, I guess it doesn't sound better for native English speaker, right?