Chapter III, Part 2. Place and Time of Celebration
25. The primary place for the eucharistic celebration for children is the church. Within the church, however, a space should be carefully chosen, if available, that will be suited to the number of participants. It should be a place where the children can act with a feeling of ease according to the requirements of a living liturgy that is suited to their age.
If the church does not satisfy these demands, it will sometimes be suitable to celebrate the eucharist with children outside a place of worship. But in that case the place chosen should be appropriate and worthy of celebration. 
26. The time of day chosen for Masses with children should correspond to the circumstances of their lives so that they may be most open to hearing the word of God and to celebrate the eucharist.
27. Weekday Mass in which children participate can certainly be celebrated with greater effect and less danger of boredom if it does not take place every day (for example, in boarding schools). Moreover, preparation can be more careful if there is a longer interval between diverse celebrations. [Notitia 1]
Sometimes it will be preferable to have common prayer, to which the children may contribute spontaneously, or else a common meditation, or a celebration of the word of God. These are ways of continuing the eucharistic celebrations already held and of leading to a deeper participation in subsequent celebrations.
28. When the number of children who celebrate the eucharist together is very great, attentive and conscious participation becomes more difficult. Therefore, if possible, several groups should be formed; these should not be set up rigidly according to age but with regard for the children's progress in religious formation and catechetical preparation.
During the week such groups may be invited to the sacrifice of the Mass on different days.