The only way you could differentiate in spoken dialogue, is context. The two sentences sound the same.
Singular and plural translations should be accepted. They can't be differentiated.
I agree with Ryan; this sentence has no indication that there's more than one person cutting the sandwiches.
I think you have had a good idea. I encourage every one to take part in your discussion, at least just to put a positive point to every case. Even better if anyone has a new example to add.
Earlier in the course we had to learn that the definite article may be there in French but English expresses exactly the same thought with or without it without it and it should be correct either way.