I want to about the following:
My daughter reached at her period some few months before while she is now 10 years and 10 months only. But she behaves very childishly; she does still playing, running, jumping, etc. And could not realize that she has become grownup and all religious matters related to her have become applicable. Even we scold her rudely besides politely advising her on this regard; it seems she does not understand. I think her mental growth is not reached that level. In this circumstances, if she misses 'Salaat' etc. Will she is punishable in the eyes of Allaah for act in this stage?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

If some signs of puberty which are mentioned in Fataawa: 87018 and 83431 appear in your daughter, she becomes obliged to perform religious obligations like prayer, fasting and other religious obligations. Her parents should inform her about her religious obligations even if she does not realize the meaning of becoming pubescent. However, if the person who reaches the age of puberty is mentally handicapped or insane then he/she is not required to perform religious obligations. The Prophet said: "The pen is lifted (stopped from writing the deeds) from three kinds of people: the sleeping person until he wakes up, the mentally-handicapped or insane person till he becomes able to reason, and the child till he grows up (reaches the age of puberty)." [At-Tirmithi]

Based on the above, we advise you, brother, to oblige your daughter to perform the prayer, wear Hijab, and carry out all other religious duties that the pubescent are required to. But if you know that she is insane, then in this case she is not required to do anything. The fact that she is playing and does not care is not a sign of being insane; rather she is doing so because she has just recently passed the age of childhood. By repeatedly advising her with wisdom and in good words, she will realize the meaning of being pubescent and the obligation of performing the prayer and wearing Hijab and performing other obligations that all other female sisters are required to do.

Allaah knows best.