But that advice - repeated in fresh guidance issued to schools this week - was the same as that issued three years ago by Gillian Shephard, the then Conservative education secretary.
Ms Morris was quoting from the present Government's 10-year strategy on drugs, drawn up by the so-called drugs czar Keith Hellawell, when she said schools should reduce the number of exclusions for drug-related incidents.
Not automatically excluding pupils the first time they are caught with drugs has been Government policy for some years.
But that did not stop John Dunford, general secretary of the Secondary Heads Association, from saying her stance could undermine school discipline. "Any kind of pressure on heads in this direction is unwelcome," he said.
Ms Morris drew a distinction between pupils found with drugs and those who were selling them. Only the latter should be expelled, she suggested. In other drug-related incidents, schools should consider a child's welfare:
"If you merely exclude, then that child may not get the support needed to reduce the cycle of dependency."
She told the conference the Government was putting #163;22.5 million into drugs education in schools over the next three years.
The guidance, Protecting Young People, urges primary and secondary schools to adopt an agreed policy on drug-related incidents.