Not smarter literally, but it opens your mind to think in ways you never have before. Mainly the right side of your brain that is in tune with creativity, and coming up with ideas. This can be a good thing in ways...I'd say most musicians probably use marijuana (we know all rappers do lol).

I'm guessing your in high school? When I first started smoking I got a little lazy too, I think it's just your body adjusting...but after awhile, it'll go away, and you'll be back to normal. Just keep it in moderation if you can.