"That is a sandwich."
Translation:Dat is een boterham.
I was able to use the link above to see the picture of a boterham. It looked "lekker" ("tasty")!
Regarding "broodje", it'll be "het broodje", won't it? It has the diminutive ending "-je" and we've been told that that ending always makes a noun neuter.
I think "broodje" is easier to remember than "boterham", at least for me. I've already memorised "het brood" ("the bread") and this is just "brood" with "-je" on the end.
Good question! I'm a native Dutch speaker. Dat and Die both mean that. A native speaker would automatically know when to use either, but it's not so easy to explain. In this sentence, Dat is used for emphasis, i.e. THAT is a sandwich. You would not say Die is een boterham. You could say Die boterham is lekker, or That sandwich is (tastes) good. If you were to say That is a man, in Dutch you'd say Dat is een man. But That man is crazy would be Die man is gek. I'm not sure how to explain this grammatically, but I hope you get what I mean.
Exactly. When we need a demonstrative pronoun (as in the examples you provided and the sentence at hand), we only use dat/dit (it's not possible to use die /deze - these two are demonstrative determiners, so they appear immediately before a noun or noun phrase -i.e. adjective+noun).
Hope this helps.