One night, a friend of mine called and asked me what the difference was between since and because. I hesitated for a second and reached for my laptop – I knew how to use them but not the hard rule. He asked after a professor marked up a paper I proofread earlier that week. Oops!
It never occurred to me there was a real difference, especially when we use them correctly without realizing it. Some hard-core grammarians would object, but because and since can almost be used interchangeably. Even Webster’s shows the word SINCE after the definition of because.
But don’t worry, there’s a rule to distinguish the two:
Since: Think of time. If you’re talking about the past, use since. T also comes after S in the alphabet, so think: since time.
a. They moved to Nashville since the hurricane hit Florida.
b. Since we were kids, we have gotten into trouble together.
c. I’ve wanted to talk to you since yesterday.
Because: Think of reason. Something happened because of something else (cause and effect).
a. We went to the store because we were out of milk.
b. I have to finish the project because I am going on vacation.
c. Because we were in love, we eloped. (yes, you can begin a sentence with because)
Sources: Grammar Bluebook, GrammarGirl
For more usage examples, enjoy a great song that uses both words correctly 🙂