Most teaching assistants went to work as normal on the first of two days of strikes by members of Unison and the ATL.
School staff walked out for the second time in a fortnight in a dispute over changes to their contracts.
The action forced the closure of 23 schools of out the 269 in the count.
However, Durham County Council has issued a statement claiming the majority of teaching assistants went to work as normal on the second round of strikes, and 20 fewer schools were closed as a result of the action than there were a fortnight ago.
Councillor Jane Brown, the council’s cabinet member for corporate services, said: “We were very disappointed to see this industrial action go ahead as we held further discussions with Unison only last week.
“We thank headteachers, governors, school staff and the majority of our teaching assistants who did report for work for helping to keep over 91% of our schools open, and minimising the disruption for parents and children.”