Dass and Das
whats the diffence
Das is the nominative and accusative singular neuter definite article (meaning "the"), so if you want to say "the house", "the child" or "I read the book", "the" would be translated as das in each example ("das Haus", "das Kind", "ich lese das Buch").
Das can also be used as a pronoun meaning "that", in examples such as "that is a big problem" or "that is a good idea" ("das ist ein großes Problem" or "das ist eine gute Idee") Basically, das as a pronoun refers back to something already mentioned.
Dass is a conjunction (a word that connects two sentences or two parts a sentence), and it is the equivalent of the English a"that", such as "He said that he was tired" or "She thinks that German is easier than French" ("Er hat gesagt, dass er müde war" or "Sie denkt, dass Deutsch einfacher als Französisch ist"). The conjunction "that" is often left out in English but can't generally left out in German.
Note that, in proper German, dass is always preceded by a comma. Note also how it changes the word order - it puts the verb to the end of the sentence.
Also, das can be used as a pronoun meaning "who" or "whom" - zum Beispiel - Dort drüben ist ein Mädchen, das ich kennenlernen will.
One has an extra "s". ;-)
Instead of me giving an answer without the correct terminology, let me provide a link which explains. https://yourdailygerman.com/2012/03/26/difference-dass-das/
This was answered a few months ago: https://www.duolingo.com/comment/20871483/Das-and-Dass
I found this thread by entering "das dass duolingo" in the Google search.