Public opinion is that w3schools is a joke (see www.w3fools.com) and I can't imagine anyone taking a certification from them seriously. Keep in my they are in no way affiliated with the w3c. A better use of your time would be creating sites on your own and developing a portfolio of work you've done.
Listen to your advisor, they (for the most part) know what they're talking about.
If you don't have a few internships under your belt or a well developed portfolio of personal work, don't bother graduating.
Get a job where you can sit and do your homework. You'll be making money while doing something you have to get done anyways.