Some of the victims reported the abuse to police after reading press reports about Peter Farrands being jailed for seven years in May 2015.
As well as working at Folville Rise Junior School in Leicester, Farrands was a scoutmaster and lay preacher.
The four victims were aged between six and 12 when Farrands abused them.
Sentencing Farrands, Judge Nicholas Dean QC said: "This was a breach of trust as a school teacher and a scoutmaster and the effect continues to haunt the victims.
"The sentence must seem lenient to the victims but they should look at the total sentence."
He pleaded guilty to seven additional charges of indecent assault against boys between 1976 and 1981.
Leicestershire Police said Farrands committed most of his crimes at Folville Rise Junior School.
Det Sgt Hazel Sandall hopes the case will encourage other victims of historical abuse to come forward.
She said: "No matter how old the offender and no matter how many years ago crimes took place, we will conduct a thorough examination of the evidence and will not hesitate to seek charges being brought against perpetrators of crime where evidence is available to us."
Two of the victims came to Leicester Crown Court, where Farrands appeared via video link, to see him sentenced.
The court heard one victim contacted the NSPCC in 2014 and said he had been abused by Farrands and two other people, who he believed have since died.
Some of the boys were assaulted multiple times.
In a statement read out in court, one of the victims said he is still receiving counselling because of what happened.
"There is still a lot of pain," he said.
"I'm still unable to enjoy the simple things like Christmas and birthdays."
A 90-year-old former teacher who is already in jail for child sex offences has had two years added to his sentence after four more victims came forward.