Carole Thorpe called for enhanced investment in education as the sector recovers from coronavirus.
The Educational Institute of Scotland asked members how difficult it was for those without a permanent job.
EIS said it was concerned about the group 'naming and shaming' individual schools and teachers.
EIS said members were alarmed and distressed but UsForThem denies the claims.
A teaching union says parents, pupils and staff need sufficient notice to prepare if another coronavirus shutdown is needed.
The EIS said measures like masks and perspex screens in schools should be considered.