I recently concluded a certificate course on web development learning HTML and basic PHP. However i discovered wordpress and noticed that i could build better websites using wordpress CMS than using what i've been taught.
My question:
Is it okay to build clients' website using wordpress and still charge normal rate? as long as i provide what they like.
Thank you, please comment.

YES!!!. As long as they get what they want. They dont have to pay for the effort you invest alone. If you get it done better with a simpler method, its to their gain also because you will deliver in time. and trust me; this matters.

first thing first. Do you know how to use wordpress? There are things to consider before using wp for clients.

First does the site required blogging or autogenrated pages? I recomend u stick to the html site while u pratic how to use wp.
Goodluck through

God bless

People are not pay for certificate. They pay for quality service rendered.

Thanks to you all. That means i can charge as I wish right?

U can not build very sophisticated web applications with wp,therefore as a good developer u shud increase ur knowledge of coding rather than tilting to cms systems like wordpress and joomla although u cud still hv their knowledge.

Microsoft's website runs in WordPress,CNN, etc and a lot, I can build very complex websites with WordPress, I even build themes from scratch, so yes you can charge your clients based on your efforts and word press is still the leading cms site with over 250 million websites built with it world wide, and am a guru programmer with the WordPress platform having being taught by Germans and Americans on its uses

There is nothing wrong with that as far is your client will be satisfied at the end.