If you've ever followed the Mass in a Missal, you may have noticed little bits like the Entrance Antiphon, Communion Antiphon or Introit, Gradual, Alleluia, Offertory and Communio. These are called the Propers of the Mass and they are meant to be sung. They have particular Gregorian chant tunes which everyone is supposed to use unless this is impossible, then they can be simplified.
If you can sing the Propers, then I want to hear from you!
In years gone by we have taken the simple way of psalm toning the propers, which seems a bit of a shame.