[FormerLib]

Clearly, the are referring to the religious education classes that are part of the Roman Catholic curriculum. The article isn't written very well so it's quite easy to confuse the details because they aren't presented very well.

Usually, non-Catholic students can opt-in for these classes but they cannot actually receive the sacraments at Mass as those are reserved for Catholic believers only.

The Catholic students apparently are being removed from the classes because they are being held to a higher standard as they will be receiving the sacraments and the combination of the classes and attendance at Mass are both required. In short, they're flunking out and are being held back in that arena.

[mlmr]

These are after-school catholic formation classes. Formerly known as CCD.