Abdul Matin, 41, of Albert Road, Wellingborough, was previously convicted of abusing two youngsters under the age of 13.
He was put on the sex offenders register and banned from working with children, both for 10 years.
Matin, who was sentenced at Derby Crown Court, was found guilty in July.
He was convicted of seven sexual assaults over 12 months from January 2007.
During his trial, Northampton Crown Court heard that Matin had touched the children sexually, kissed them, and forced one of them on to his lap.
Police were first alerted to the case after one of the children told a school teacher about the classes.
Matin, who came to Britain from Bangladesh in 2004, had constantly denied the claims and said the children had invented the allegations.
Rebecca Herbert, prosecuting, told Matin: “You thought you would be completely above suspicion; you thought you could get away with it, get away with touching these [children].”