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.
We have already issued Fatwa 86533 on how a Muslim should spend his spare time, so please refer to it. The best thing on which children should spend their time during holidays is attending circles of memorization of the Quran. The Prophet said: "The best of you are those who learn Quran and teach it". [Al-Bukhari] Moreover, giving recreation to children by letting them do permissible entertainment is something needed, as this renews their motivation, urges them to be energetic, and makes them welcome studies with a high interest and motivation. So there is no harm in taking them to parks and children play areas provided that these places are free from prohibitions, like music and the like; this is something possible if a person chooses the right time of taking them.
The parents could also advise their children to practise any type of sport which will make them fit and healthy, or teach them a craft that suits their age and bodily strength. If children organize their time well, they would be able to grasp much of what is mentioned, the most important of which is attending circles of memorization of the Quran.
Allaah Knows best.