Why did Emperor Taizong teach Li Zhiru when he was a child?

Emperor Taizong was in this dilemma. Every time I get wise, I just think he is naive and helpless, just like a boy, who wants to inculcate. Therefore, whenever he meets the right occasion, he is often inspired by the topic. When he saw Li Zhi eating, he said, "You have to know the hardships of the draft to have food all the time." Seeing Li Zhi riding a horse, he said, "You should know that a horse is tired and hard. Don't let it run out of energy. Let Kyle ride it often." Seeing Li Zhi in the boat, he said, "Water can carry a boat, but it can also overturn it. People are like water and you are like a boat. " Seeing Li Zhi taking a nap under a tree, he said, "The integrity of wood can only be seen with the ink rope as the criterion, and you can only see it with coachable."