Standing singing posture

Standing singing posture is based on the upright standing posture. Stand with your legs slightly apart (to gain better stability) with gently straight but not bent knees. It is often recommended to place one foot a little in front of the other in order to gain better stability. Body weight is distributed to both legs, concentrating rather at the toes of your feet (not the heels). The breast bone P6 is pushed out slightly, shoulders relaxed, hands hang loosely. The buttocks need to be tucked under. The head is upright on a relaxed, gently extended neck (as if someone were pulling your head up by the hair on its top P1).

Exercise 13 - Playing king

Since children like fairy tales, you can use an imaginary king or a princess to explain the idea of an upright singing posture.
First try to act out the character standing standing in one place, later you can attempt walking. D20

Story for younger children:
Imagine you are a king (a princess) watching your people from the balcony of your palace. The king however, never leans from the balcony like a common man. He always holds his head high in a kingly upright position (avoid a fiercely protruding chin), and gazes at the endless crowd in the distance. Now the king turns his head, looking to the right where the queen stands, then turns it slowly to the left where the prince is. Then the king turns around slowly and majestically walks into his chamber, where he slowly stops. All this time, the king must maintain his majestic but not cramped body posture. D21

Exercise 14 - Exercise to induce singing posture

If the children are unable to perform the singing posture on their own, you can help them with a simple trick. Take a wooden or a bamboo stick around 70 cm long and fix it between their backs and slightly bent arms, as shown in the following video. Holding this stick without letting it fall will make the children form the desired posture easily.. D22
Now return to the previous exercise and play the king once again with the help of the stick.
Always make sure that the children's posture and movements are not stiff; pay particular attention to the relaxed neck.

If the child feels particularly uneasy about this exercise, it very likely suggests flabby back muscles and contracted intercostal muscles. Rounded shoulders and a narrowed rib cage are typical symptoms of this defect. Such a child is incapable to naturally stand in a correct singing posture until the relevant muscles are trained.
In such a case, I recommend practicing the Exercises to restore the proper muscle functions which should make a correct body posture a natural thing for the child. Children should be standing upright not to please you but for their own sake.