Where pupils have part-time education at a PRU or external EOTAS provider and mainstream school, many pupils do not attend their mainstream school when they should.
Pan mae disgyblion yn cael addysg ran-amser mewn UCD neu ddarparwr AHY allanol ac ysgol brif ffrwd, nid yw llawer o ddisgyblion yn mynychu eu hysgol brif ffrwd pan y dylent.