In Bradford on Avon, St Laurence School will be closed to Year 7, 8 and 9 pupils.
The school is open to Years 10 to 13 today.
Headteacher Fergus Stewart said in a letter to parents: “We have considered the situation very carefully, bearing in mind the impact of strike action on timetabled classes and the welfare of pupils, and have decided that we will be able to remain partially open on that day.
“We realise that this will be very inconvenient for many families and for that we apologise.”
Kingdown School in Warminster will be open for Years 11, 12 and 13, but will be closed to students in the other year groups.
However, space will be provided for pupils in Year 7 to work under supervision.