Weil, dass & wenn
Weil (because), dass (that), and wenn (if/when) send the finite verb to the end of the subordinate clause. Put a comma before the clause. If the subordinate clause comes first, the main verb follows the comma.
Understand the idea
A subordinate clause depends on another clause and begins with a connector such as weil, dass or wenn. Its finite verb normally appears at the end. The main clause keeps its own finite verb; one verb cannot do the job of both clauses.
Build it step by step
Choose a connector for the intended relationship, then build each clause separately. In a basic subordinate clause, move the conjugated verb after its other material. If the subordinate clause comes first, it occupies the first main-clause element, so the following main clause begins with its finite verb. Separate the clauses with a comma.
See it in a sentence
Ich weiß, dass er heute kommt.
Ich bleibe zu Hause, weil ich krank bin.
A useful memory aid
Underline one finite verb in each clause. Check their positions independently rather than rearranging the whole sentence at once.
A common trap
Do not place a subject before the main-clause verb after an initial wenn-clause. Also distinguish weil's verb-final order from denn's main-clause order.