The Main Clause
Recognize a main clause when you see one.
Diane kicked the soda machine.
Diane = the subject; kicked = the verb.
A giant spider has made its home behind the shampoo bottle in Neil's bathroom.
Spider = the subject; has made = the verb.
Sima and Michele are skipping their chemistry class to sit by the lake and watch the sun sparkle on the water.
Sima, Michele = the subjects; are skipping = the verb.
Remember this important point:
A sentence can contain any number of other grammatical units, such as participle phrases, prepositional phrases, subordinate clauses, appositives, etc. It must, however, contain at least one main clause. Take a look at the example below:
While dissecting a cow heart in her anatomy and physiology class, Shenicka realized that a cheeseburger, her favorite lunch, was no longer appetizing.
While dissecting a cow heart = participle phrase.
In her anatomy and physiology class = prepositional phrase.
Shenicka realized = the essential main clause.
That a cheeseburger was no longer appetizing = subordinate clause.
Her favorite lunch = appositive.
Do not confuse a main clause with a subordinate clause.
When you place a subordinate conjunction in front of a subject and verb, you will no longer have a complete thought. The group of words becomes a subordinate clause, like these examples:
When Diane kicked the soda machine ...
When Diane kicked it, what happened? Did the soda machine cough up her drink? Did the soda machine fall on top of poor Diane, crushing her underneath? Did quarters start shooting out of the coin return slot? Because you no longer have a complete thought, you no longer have a main clause.
Because a giant spider has made its home behind the shampoo bottle in Neil's bathroom ...
Because the giant spider lives there now, what has happened? Did Neil buy a can of insecticide? Does Neil now refuse to bathe? Is the spider starving because there are not enough insects for her to eat? The word because, a subordinate conjunction, leaves the idea unfinished, so you no longer have a main clause.
Even though Sima and Michele are skipping their chemistry class to sit by the lake and watch the sun sparkle on the water ...
Even though Sima and Michele are skipping their chemistry class, what else are they doing? Are they also studying their notes? Are they contemplating how the water in the lake is composed of hydrogen and oxygen atoms? Are they gossiping about their teacher? The addition of even though makes a subordinate clause.