Princes from faraway kingdoms began coming to Hastinapura to take lessons under this most distinguished guru. Drona taught them various warfare skills such as horse riding, elephant riding, javelin throwing, dueling, defense and offense, mace fighting, and archery. Charioteer Adhiratha's son, Karna, also learned alongside the princes. Karna was always jealous of Arjuna and never missed an opportunity to criticize him.
One day, Dronacharya decided to conduct an archery test for his students. He placed a bird-shaped doll on a tree branch and told his students, "I will summon you one by one. At my command, aim for the bird's eye."
Drona summoned Yudhishthira first. Yudhishthira stepped forward and nocked an arrow.
"Don't shoot until I tell you," Drona said. "First, tell me what you see."
"I can see the tree, the bird, my bow, my arrow, my hand, and you," answered Yudhishthira.
"Okay, you may go," Drona told Yudhishthira, then summoned Duryodhana. He asked him the same question and repeated the process with several other princes. All of them, including Karna, gave roughly the same answer as Yudhishthira, after which Drona told them to leave.
Finally, he summoned Arjuna. After Arjuna nocked his arrow, Drona asked him, "What do you see? Do you see me, your classmates, or anything else?"
"I can't see anything except the bird's eye," replied Arjuna.
"Excellent! Now, shoot," he instructed.
The arrow hit its target, and the doll fell to the ground. Drona hugged Arjuna and said, "I have made you the best archer in the world. Promise me one thing."
"Anything, Gurudeva."
"In the future, even if you face me in battle, fight to win and do not back down."
"I promise, Gurudeva," replied Arjuna.