What the name of this cartoon show?

I used to watch it when I was younger and I think it was on the same channel as courage the cowardly dog and the grim adventures of billy and Mandy Anyways It's about this dragon dude who goes to school as a normal teen boy and ha a crush on this girl who is secretly the ninja working for his worst enemy and at home he can turn into a dragon like his little sister and he gets trained by this little short old Chinese man who I thin is his grandpa I only remember bits and I really want to know the name of it please help