It was not unusual for some children to be absent from school for weeks or months at a time. Sometimes this was due to illnessess which were common in Victorian times but which are thankfully rare nowadays.
This example comes from the records of Llandewi'r Cwm School for November 1889...

5th November - "Theophilus Jones and David Griffiths returned to School after (Jones) ten months, and (Griffiths) three months absence".
The school Log Book doesn't say why these boys were away for so long, but illness was a likely cause. But sometimes the parents didn't care much about schooling for their children...

The above entry comes from the Log Book of Llanganten Board School for 1883. The Lennard and Evans families must have had at least two children each on the books of this school, though they probably didn't turn up for school very often !
Some parents just wanted their children to help out on the farm or at home, and then get a paid job as soon as they were old enough to help support the family.
There are more examples of stayaway children on the next page...

Trouble with the girls as well...