Story of Arjuna

Childhood
The princes grew into wonderful children. After thread ceremony, they all went for studies to the ashrama of their Guru Acharya Drona (also called Dronacharya) - Teacher of the Royal family. Dronacharya was well versed in ancient scriptures -- Vedas and Upanishads, as well as in practices of Yogas and Meditation. Besides he was adept in various martial and other arts useful in war time, useful in defence and attack. In particular, Acharya Drona was the supreme authority on training his disciples in the art of archery.

Story of Arjuna
Out of all Pandavas and Kauravas, Arjuna had immense liking for the sport of bow and arrow. He practiced this art with great concentration and perseverance. Soon he became numero uno in this art. Acharya Drona was very much pleased with Arjuna and showed preferential love and favour towards him. This caused a natural adolescence jealousy in the heart of Duryodhana and his brother Dushasana. Duryodhana, in particular, did not like Arjuna and other Pandavas and silently ill feelings like hatred towards Pandavas took birth in his heart.
One day they openly criticized their Guru for favour shown towards Arjuna, telling him they also were not less skillful in archery. As a reply to their criticism, Acharya Drona arranged a test to decide the best archer amongst all.
Accordingly, a wooden bird was put on a branch of a distant tree. It was partly hidden by the foliage. A prominent artificial eye was painted on the wooden bird. The teacher called all his disciples and said, "Look my children, a bird is sitting on that far off tree. You have to hit the arrow exactly in its eye. Are you ready?"
Everyone nodded. First the eldest Yudhisthira was invited to try his skill. He stretched his bow-string and was about to release the arrow when Dronacharya asked him a question, "O eldest son of Kunti, may I know what is visible to you at this point of time?"
Yudhisthira replied innocently, "Why, O Gurudev, I am seeing you, the tree, people around me, and the bird!"
Similar questions were put to Duryodhana, Bhima, Nakul, Sahadeva and others, and Acharya Drona got the similar answers as those given by Yudhisthira. Acharya told them to step aside as it was obvious that with such poor concentration they were sure to miss the target!
Lastly, it was the turn of Arjuna. He readied himself, his bow and arrow in perfect graceful harmony! When the Guru asked him, "O Arjuna, will you tell me what is being observed by you?"
And Arjuna replied, "Sir, at this point of time only the eye of the bird is visible to me." When asked by the teacher whether he was able to see the bird, the tree, and people around, Arjuna replied in negative maintaining that he saw the eye of the bird only.
Dronacharya was pleased with Arjuna's immense concentration and correct approach towards the art of archery. He then explained to others how due to such peculiar yogic qualities and powers he preferred Arjuna as his best disciple.
Everyone saw the point, including Duryodhana; but the seed of jealousy was sown in his heart. In his attempt to equal Arjuna and other Pandavas, Duryodhana fell victim to anger and similar base emotions the effect of which would sure to show later in our story.