While wandering around seeking knowledge and the art of warfare, Karan heard the name of Dronacharya's Gurukul.Dronacharya had heard the name of Karan from other gurus, who roamed around in search of knowledge and art of weapons, so dronacharya admitted Karan to his Gurukul.
He improved his skills immensely under Dronacharya's half-hearted tutelage. Karna went toe-to-toe with Arjun on practically everything. They were part of different cohorts, but you know how it is at Gurukul. You still hang out with the other students – to share notes, to help with homework, and to criticize the professors. That's how Karna started to get to know the Pandavas and the Kauravas, from a distance at first. But Duryodhan welcomed him further into their midst. It's.
Though Karna competed heavily with Arjun and even managed to match Arjun's accomplishments on the training grounds, he never really impressed Dronacharya quite the way Arjun had.