This sentence is full of prepositional phrases. They are: [over the river], [through the woods], [to Grandmother's house]. These prepositional phrases are all a dependent clause because they do not contain the subject and verb of the sentence. The dependent clause is "we'll go". It contains the subject - We and the verb phrase "will go". A dependent clause is a complete sentence that can stand on its own. An independent clause needs more for it to be a dependent clause.
