Two boys playing basketball in Pickering Lodge Park in Timperley were approached by four offenders all from around the Stretford area on Aug 21 at around 6pm.
They tried to take a high value mountain bike, and this is when the 16-year-old boy was knifed in the chest.
The offenders still took the mountain bike and made off leaving the 16-year-old boy on the floor in a bad state, at the time he was taken to hospital in a critical but stable condition.
Police have now charged three boys with section 18 assault and robbery.
For a general guide to how those under 18 are sentenced and a guide please click HERE