Amit Kumar Behera

Sir, as your kid is in class 1st, he is curious about the knowledge as he can grasp things quickly. But, coming to his patience, he cannot sit in a place for a longer time. It shows that your kid is an active learner; he wants to study by doing activities. To develop his patience, you need to engage your kid in the action where he is involved. While teaching, give him additional ways to study, e.g. if he is learning numbers, show some videos, so he is engaging in it. The moment he doesn't feel the subject interesting, he will not sit in one place.
At this age, the ability to retain things is high in kids, so any time he is studying makes sure he learns effectively. Ie. If he is studying for the 15 min, make sure this 15 min is effectively used video, games, question for his study. Just bring out the kids interest. He will sit with patience.
Kids watch cartoon for a long time because they feel cartoon interesting, so like you just need to develop his interest. His interest will do the rest.