The no-notice inspections were carried out at the request of the Department for Education and are not part of the standard inspection regime.
The DfE had asked for a number of independent schools to be inspected.
Results of the inspections of the two secondary schools and one primary school will be released within weeks.
Earlier this week Ofsted chief Sir Michael Wilshaw said inspections would be undertaken more frequently because of concerns raised by the alleged Trojan Horse plot.
This involved claims that a number of schools in Birmingham faced takeovers by groups with a hardline Islamic agenda.