Children should be taught to worship twice a day once in morning after taking bath and before having food and the same way in the evening at dawn after games and before studies. However, I do not think prayer can be forced upon children- it should be something they willingly participate in. Prayer is not for everyone.
Some people find spiritual growth through other means.
Parents should make Children prayer a habit, the question is not once or twice. Moreover meditation is the best thing for any one either for kid or for a grownup, this should be 24 hrs activity. Indian heritage which is being renowed all over the world why not it is possible for an Indian. Parents should indulge their children in their daily prayers and take them to the temple,church or mosques along with them. They should be taught to respect people of other religions too.