Troublemaking pupils should be excluded from school for as much as a year, rather than a few days, research suggests.
Short-term suspensions disrupt children's education and do little to improve their behaviour, according to a report by the Centre for Policy Studies (CPS).
As a result, teachers are forced to help these pupils catch up with what they have missed - while facing poor behaviour and resentment from the child.
Instead badly behaved pupils should be suspended for a year and taught in an alternative setting, such as a Pupil Referral Unit (PRU), it says.
The study says: "Fixed term expulsions of a few days are too short a time for even a successful provider to make much mark; very little can be done in less than a year.
"Not only is an absence of a few days disruptive to the child's progress academically, it also seems to have little disciplinary effect upon those who are being excluded on a regular basis.
"Returning children who have learnt little during their absence (and not altered their troublesome behaviour) to the same classrooms from which they were banished, seems to conform to Einstein's description of madness: 'doing the same thing over and over again and expecting different results'.
"Their teachers merely end up having to provide extra support to help them pick up what they have missed, against a tide of increasing resentment, insecurity, and poor behaviour from the child."
The study, Children Behaving Better, says that excluded children are likely to have very poor results, with just 1% of 15-year-olds taught in PRU's receiving at least five GCSEs at grade C or higher in 2006.
It says the poor results of PRU's, and that more than 12,000 children receive five or more suspensions in a year suggests that "short fixed-term exclusions do not work."