Guidelines are to be issued for teachers advising them about the warning signs that a pupil is being forced into marriage.
The Forced Marriage Unit deals with around 250 cases a year
The guidelines were unveiled as the Forced Marriage Unit was relaunched.
Set up by the Foreign Office in 2000, it is now run jointly with the Home Office.
It deals with around 250 suspected cases a year, most of which involve links to south Asian countries such as Pakistan, Bangladesh or India.
The new joint Forced Marriage Unit has a staff of six and an annual budget of £300,000.
Home Secretary Charles Clarke was among those at the unit's relaunch at the Foreign and Commonwealth Office on Wednesday.
"This is an important step to tackling forced marriage in this sector of public life.
"Forced marriage is nothing less than an abuse of human rights. It can involve serious forms of duress, including physical assault," Mr Clarke said.
The teachers' guidelines, to be sent to secondary schools next month, set out the "warning signs" of forced marriage.
Homework may suffer and pupils may be anxious, depressed and emotionally withdrawn. They may start harming themselves, develop anorexia or begin shoplifting or substance abuse," the document states.
Teachers are also warned to look out for a family history of older siblings leaving education early and marrying early.
The guidance is one of a series of initiatives introduced by the government to combat forced marriages.
Other measures currently being considered include creating a specific offence of coercing someone into marriage and raising the minimum age that a foreigner can enter the country as a spouse from 16 to 18.
A forced marriage is one conducted without the full consent of both parties and under duress.
At present, anyone found guilty of forcing someone into marriage can be prosecuted for kidnap, false imprisonment or rape.
In the year to April 2004, approximately 200 young Britons were rescued, resettled or repatriated from south Asian countries.