The accident happened on the M1 south of junction 23 at Loughborough in Leicestershire just before 9.30am. The coach driver and a teacher were cut free from the wreckage and were taken to Leicester Royal Infirmary with broken legs. Twelve pupils from Kilburn Junior School near Belper in Derbyshire, were slightly injured.
Another 27 children - aged seven to 11 - escaped with minor scratches and shock. They were also taken to the Leicester Royal Infirmary but were expected to return home yesterday.
A spokesman for Derbyshire County Council said two coaches from Kilburn Junior School were en route to Gravelines, near Calais, northern France, when the accident happened. The week-long trip has now been cancelled.