Questions & Answers about Wir brauchen Holz, das sehr stabil ist.
Why is it das with one 's' instead of dass?
Here, das is a relative pronoun meaning 'that' or 'which'. It points back to the neuter noun Holz. You only use dass (with a double 's') as a conjunction meaning 'that' to introduce a dependent clause, like in Ich denke, dass... (I think that...).
Why doesn't stabil have an ending like stabiles to match the neuter noun Holz?
Adjectives in German only take endings when they come directly before the noun they describe (like in ein stabiles Holz). When the adjective comes after a verb like ist (is), it is a predicate adjective and stays in its basic dictionary form, stabil.
Why does the verb ist go at the very end of the sentence?
The phrase das sehr stabil ist is a relative clause, which is a type of subordinate clause used to describe a noun. In German, the conjugated verb always gets pushed to the very end of a subordinate clause.
How would I turn this into a suggestion like 'Let's find wood...' using the Lass uns grammar from this lesson?
You would change the main clause to use Lass uns (Let's) followed by the infinitive of the action verb at the end of that main clause. For example: Lass uns Holz finden, das sehr stabil ist. Notice that the relative clause describing the wood doesn't change at all!