Learn German: Ich weiß nicht, wie der Schredder den Schrott zermahlt. - I do not know how the shredder grinds up the scrap.

In German, wissen is used for knowing facts or knowing how something happens, which is usually followed by a question word like the wie (how) in this sentence. kennen is used for being familiar or acquainted with a person, place, or thing.

Why does the verb zermahlt go at the very end of the sentence?

The word wie (how) introduces a subordinate clause. In German, subordinate clauses require the conjugated verb to be kicked to the very end of the sentence. The main clause is Ich weiß nicht, and the dependent clause is everything after the comma.

Why is it der Schredder but den Schrott?

Both words are masculine nouns. Schredder is in the nominative case because it is the subject doing the action (the machine doing the grinding). Schrott (scrap) is in the accusative case because it is the direct object receiving the action (the material being ground up), so its article changes to den.

What does the prefix zer- in zermahlt add to the meaning?

The inseparable prefix zer- usually indicates destruction, breaking into pieces, or dissolving. Here, it adds to the base verb mahlen (to grind or mill) to create zermahlen, which emphasizes grinding something up or crushing it into pieces.