Introducing Drona and his appointment as the teacher of Kauravas, Pandavas and other princes is full of drama. We all know the story of how he pulls out a ball from the well by making a rope of arrows by shooting them one behind the other . (Samhita says it is reeds of grass that were used and were shot after chanting a mantra!)
When the kids, amazed with his remarkable feat, want to know who he is, he tells them 'Just go to your grandfather and tell him what happened here. He will know who I am'. (Drona is not lacking vanity!) When Bheeshma hears the story from the excited kids, he instantly recognises that it is Drona and hurries to meet him and welcomes him to Hastinapura.
To set records straight, Kripa their teacher in the use of arms, is the twin brother of Kripi. Drona is the husband of Kripi. Kripa and Kripi were brought up by Santanu. He found them in the forest and they are the children of great Gautama.
(This brief introduction is mystifying. There is no explanation why they were left in the forest by their father. Probably it will appear later in the story.
I remember watching on Discovery channel a program called the myth busters. They were trying to confirm whether the myth of splitting an arrow which is already on the target, by shooting another on it was really true. None of the archers who tried were skilled enough to accomplish this feat. Hence a machine was rigged and after many trials they were able to succeed. The second arrow shot was able to split the earlier one, but it did not stick there. The machine was accurate in direction but was not designed to control the speed of impact! We can only marvel at Drona and his superior skills in archery to consistently do this. He of course knew the right mantra!)