Sally Knox's son Rob died in 2008, when he was stabbed to death in a fight outside the Metro Bar in Sidcup, south-east London.
Speaking to Daybreak about the Government's plans to reward inmates on merit she said prisoners should be "should be spending more time in their cell thinking about what they did, and the other thing is there needs to be more education and training."
She added: "What are we achieving by giving prisoners satellite TV to behave?"
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A 23-year-old man has been arrested in connection with the attack at Manchester Arena last night.
Theresa May says police think they know identity of lone bomber as she contrasts "warped" terrorist with courageous emergency services.
Donald Trump has branded those who take part in terrorist acts as "evil losers" in the wake of a suicide attack at Manchester Arena.