Worship and devotion
The Mass
The Importance and Dignity of the Eucharistic Celebration
16: The celebration of Mass, as the action of Christ and the people of God arrayed hierarchically, is for the Church universal and local, as well as for each of the faithful, the centre of the whole Christian life. For the Mass contains the high point both of the action by which God sanctifies the world in Christ and of the worship that the human race offers to the Father, adoring him through Christ, the Son of God, in the Holy Spirit. During the cycle of the year, moreover, the mysteries of redemption are recalled in the Mass in such a way that they are in some way made present. Furthermore, all other sacred actions and all the works of the Christian life are linked with the Eucharistic celebration, flow from it, and have it as their end.
(From the General Instruction to the Roman Missal)
4: The Church celebrates the paschal mystery on the first day of the week, known as the Lord's Day or Sunday. This follows a tradition handed down from the apostles and having its origin from the day of Christ's resurrection. Thus Sunday must be ranked as the first holyday of all.[3]
(From the General Instruction to the Roman Missal, General Norms for the Liturgical Year and the Calendar )
Masses With Adults in Which Children Also Participate
17: “ … if the place itself and the nature of the community permit, it will be appropriate to celebrate the Liturgy of the Word, including a homily, with the children in a separate, but not too distant, room. Then, before the Eucharistic Liturgy begins, the children are led to the place where the adults have meanwhile celebrated their own Liturgy of the Word.”
(from Directory for Masses with Children, Chapter II)