It’s mentioned, just not dwelled on. It’s mentioned once in passing in each of the first two books:
Sorceror’s Stone:
They piled so much homework on them that the Easter holidays weren’t nearly as much fun as the Christmas ones.
Chamber of Secrets:
The second years were given something new to think about during the Easter holidays.
And so on. It’s just that I don’t think anything interesting ever happens during them.
It’s mentioned, just not dwelled on. It’s mentioned once in passing in each of the first two books:
Sorceror’s Stone:
Chamber of Secrets:
And so on. It’s just that I don’t think anything interesting ever happens during them.