It would have been nice to have seen the word "sedicenni" (sixteen-year-olds) before this exercise appeared. It was impossible to guess based on the dictionary hints and previous lessons.
Why not loro hanno sedici anni?
you are right, it is correct too and should be accepted. Did you report it?
It is accepted now, January 23, 2014.
Thanks for letting us know.
I'm wondering this too. Sounds like a good translation but maybe not idiomatic?
Yet another idiomatic expression tested without any prior introduction.
"Old" without an "s" !!! and perhaps "year" with an "s" ...???