The teenager, who cannot be named due to his age, was appearing at Barkingside magistrates’ court, 10 days after Explorer Scout Jodie was killed.
The 17-year-old was playing music with friends near a children’s playground at Harold Hill, Romford, when she was approached from behind and stabbed.
A 20-year-old man, Manuel Petrovic, of Romford, was also charged with her murder last week and appeared at the Old Bailey today.
He appeared via videolink from HMP Pentonville and spoke only to confirm his name, age, and Croatian nationality.
The Recorder of London, Judge Nicholas Hilliard QC, remanded him in custody until a plea hearing on May 28 and set a provisional trial date for September 2.
A further four arrests were made yesterday in connection with the investigation. Among them was an 18-year-old from Romford, who was being questioned in custody today on suspicion of murder.
A 50-year-old man and 38-year-old woman, both from Dagenham, and a 17-year-old boy, were also being quizzed on suspicion of assisting an offender.
Purple ribbons were attached to the railings outside the Old Bailey today by anti-knife crime campaigners in tribute to Jodie. Lacey Rigby, who put up the ribbons, said they are planning to start patrolling the streets wearing stab vests in a bid to convince young people to hand over knives.
“If we can collect three knives a week, then that’s possibly three lives we have saved,” she said.
In another weekend of violence in the capital, a 20-year-old Romanian man died after being assaulted outside Queensbury Tube station.
The victim was said to have been punched in a brawl as he returned home from a night out. Police were called at about 12.30am yesterday.
Medics battled to save him but he died a short time later in hospital. There were no arrests.
Siva Ratnam, 68, who owns a shop near the scene of the attack, said the victim was assaulted when a fight broke out between two groups of men.
Mr Ratman told the Standard the victim had gone into his shop with friends before being attacked. He said: “The men were nice and well-behaved. They had come from a club in Edgware and were getting some drinks and food.
“They all went outside and then the other men came and they had a fight.”
His death came hours after a 19-year-old man was left seriously injured after being stabbed in front of passengers on a 134 bus in Muswell Hill. A boy aged 17 has been arrested.
In a separate incident, another 19-year-old man was injured after being stabbed in East Dulwich yesterday afternoon.
Today police forces began a week-long nationwide blitz on knife crime, codenamed Operation Sceptre. Officers will use surrender bins, stop-and-search powers, carry out weapons sweeps and target habitual blade carriers.