Wooden bird

One day Drona had a bird made from wood and had that placed on the top of a tree. He called his disciples one by one, First came Yudhistira. He asked him to aim and cut off the head of the bird when he gave the signal. He asked the prince to take aim at the bird and then asked what did he see. The prince said he saw the bird on the tree, on the ground he saw Drona and the princes.
Duryodhana, Bhima and the other princes came one by one and all said what Yudhistira had said.
Drone asked all of them to go back.
In the end Drona called Arjuna.He asked Arjuna to take aim and then asked what he saw. Arjuan said he saw only the bird. What part of the bird? Arjuna said he saw only the head with eyes.

Drona asked Arjuna to shoot. The head of the bird was cut. Drona embraced Arjuna.

One day the princes and Drona had gone to the river to bathe. A crocodile caught Drona's leg in its mouth and started pulling him. While the other princes were not sure what to do, Arjuna shot five arrows together and cut off the crocodile into pieces.

Drona came up and pleased with Arjuna gave him a weapon called Brahmashira. He asked Arjuna to use this only on celestial beings and never on humans.

Seeing Arjuna being praised, Duryodhana was angry.

Drone kept on teaching the princes. Yudhistira became an expert in handling the chariots. Duyodhana and Bhima were experts in handling the mace. Nakula mastered the art of handling horses and Sahadeva mastered the use of the sword.

Arjuna mastered all weapons.