Other forms: compound-complex sentences
A sentence with at least two independent clauses and one dependent clause is a compound-complex sentence. If you really want to impress your English teacher, include a compound-complex sentence or two in your essay!
A compound sentence joins independent clauses, each of which could be its own stand-alone sentence, usually with a coordinating conjunction (for, and, nor, but, or, yet, so). A complex sentence combines an independent clause with a dependent clause, one that cannot stand alone because it does not express a complete thought. A compound-complex sentence does both: "While I was walking to school, my sister sang show tunes, and I sang along." The first clause, "While I was walking to school," is dependent (it's not a complete sentence on its own because it starts with "While"), and the second two clauses, "my sister sang show tunes" and "I sang along," are independent clauses. So the whole sentence is a compound-complex sentence.