"That room is large."
Translation:Tuo huone on suuri.
See this discussion: https://forum.duolingo.com/comment/42143221 Q: Can iso and suuri be used interchangably? A: Not always. It's a bit like big and great: one is generally used for more concrete and not quite so large things, the other for more theoretical concepts and really sizeable stuff. So dreams and visions and mountains tend to be suuri, and dogs and stones iso. There are also differences between dialects, as well as a recent tendency to use iso in contexts where suuri would previously have been the norm. But for the purposes of this course, both are accepted, at least in most places.
There are two different "that" in English:
"That" used to point out a specific thing ("that room") which is "tuo" in Finnish
"That" used to bind phrases together ("I have a feeling that something is going to happen") which is "että" in Finnish
So in this case, it can only be "tuo", not "että".
Edit: For more information, the first "that" is a (spatially deictic) demonstrative https://en.wikipedia.org/wiki/Demonstrative https://en.wikipedia.org/wiki/Deixis#Spatial_deixis
The second "that" is a conjunction https://en.wikipedia.org/wiki/Conjunction_(grammar)