First of all, from a physiological point of view, it is best for children to learn sketch after they grow up and mature psychologically, that is, after 10, it is best to start from the fourth grade of primary school at the earliest, and boys may be a little later. The reason for this is the following：

(1) sketch learning is a long process, and a primary sketch assignment takes about two hours. This is a boring thing for most children, which often makes them bored with sketch learning, which is not conducive to their further study.

(2) Sketching is not only hand-drawing, but also thinking and judging with all your energy. At the same time, the coordination of human hands and brains can only be formed after they grow up and mature. Therefore, learning sketch too early will prolong the study time and bring unnecessary waste.

(3) Starting sketch learning too early, children lack the ability of self-study and mutual learning, and relatively lack the choice of good learning environment and teaching conditions. If children can't accept scientific and standardized learning methods, they will form bad study habits and improper technical operation. Correcting these problems will be more difficult than learning from scratch.

So the teacher thinks that the time to start learning is sometimes not as early as possible. When children seriously accept knowledge, it is the right time.