Akon Guode is on trial for killing three of her children. Picture: Supplied

Akon Guode, 37, has been charged with three counts of murder after her one-year-old son, Bol, and four-year-old twins, Hanger and her brother Madit, died on April 8 last year.

She is also charged with the attempted murder of her six-year-old daughter Alual, who survived after being pulled from the water at Wyndham Vale with her mother.

One-year-old Bol and four-year-old twins Madit and Hanger died after the 4WD they were in crashed into a lake at Wyndham Vale in Melbourne's outer west. Picture: TwitterSource:Twitter

Guode denies driving into the lake on purpose and blames a dizzy spell for the accident.

Viveka Simpson, the former biology teacher of Guode’s eldest daughter Akoi Chabiet, told the court the teen had raised concerns about her mother’s ability to drive just months before the incident. Ms Simpson said she had become somewhat of a mentor for the teenager and spoke to her about her home life after noticing her school work had been slipping.

The usually conscientious student, then in year 11, had taken on the role of mother because Guode struggled to get out of bed which meant the teen’s school work had considerably changed, Ms Simpson told the court on Wednesday.

Akoi had told her on numerous occasions that her mother was “unwell” or “depressed” and received little support from the father of her four youngest children or the greater Sudanese community. That lack of support meant the teenager needed to prepare all family meals and feed her younger siblings as well as manage her younger sister’s diabetes.

Police divers prepare to remove Akon Guode's car after it plunged into a lake off Manor Lakes Boulevarde. Picture: Mark StewartSource:News Corp Australia

The mother-of-seven sobbed in the dock as Ms Simpson detailed the lack of support Guode received from the Sudanese community after her affair with the children’s father.

The pair kept in touch and caught up for coffee on the day Akoi’s year 12 results were released in December 2014.

On that day, Akoi told Ms Simpson she needed to get her licence because “mum shouldn’t be driving” after she suffered dizzy spells and blurred vision while driving, the court heard.

Akoi again visited Ms Simpson at school a week after the children’s deaths in 2015.

She couldn’t believe what had occurred and seemed angry that the father of the children had featured on television, especially given the teenager’s view that he spent little time with the children, Ms Simpson said.

The committal hearing continues.