Amid the gently swaying palm trees of the Indian Ocean island of Zanzibar sits a school with a difference. The Raha Leo Alternative Learning Centre provides training to young students who may have otherwise missed out on education altogether.

Take 21-year-old Hadia Baruti Wimbi. She left her parents' home when she was only six.

"An elderly member of my family came to see my parents, asking if she could take me away. She promised my parents that she would enrol me at school. When she became my guardian, she enrolled her own children, but not me," Hadia said.

Sad to see her friends going off to class, Hadia confided in her uncle. "I was 13; he came to get me and entrusted me to a teacher," she said.

But she was way behind in her learning, and far older than the other students at her primary level.

"It took me a year to persuade her to go to school. She didn't want to go, because she felt too old,” said Fatima Rashid Ali, the teacher who took her in. “I told her that a traditional school would not suit her, but I knew of a centre that offered an alternative way of learning."

Like other girls, Hadia used the Raha Leo Alternative Centre, a boarding school funded by the African Development Bank, as a pathway to catch up and give herself a chance of success in life.

"If I hadn't come to this centre, I would have spent my life doing domestic work. Now, I can read and write. I'm sure that once I've finished my studies, I'll be able to set up my own business. I'm so glad to have studied here," she said.

Tanzania has around a dozen learning and training centres for young people. The African Development Bank granted the country $32.7 million in funding to build two vocational training centres with the necessary equipment. The Bank has also contributed to improving teachers' manuals. Starting with around a dozen boarders at first, the centres have grown and now have more than 2,000 students gaining a basic education.

"We had just 32 students in the Raha Leo Alternative Learning Centre when we opened in 2006. Every one of them had dropped out of school. Nearly 95% of them had become separated from their families. Today, we try to get close to them, to show them our affection and teach them things," said Kazija Salmin Ufuzo, a teacher of Swahili and mathematics at the centre.

She said that the aim was to teach students to read, write and master basic numeracy. But students need other skills too: "We have launched programmes such as homecraft, computer maintenance, agriculture, carpentry, electrical installation, cookery and sewing,"

Madina Mjaka Mwinyi, principal assistant at the Ministry of Education and Vocational Training of Zanzibar added: "We can say that 85% of the young people who we have trained in the different centres have set up a business. With a diploma, they are able to make a go of things.”

The programme has provided more than 6,000 interest-free micro-loans to students, most of them women, to start businesses.

Former student Subira Haji Khamisi gained a qualification in tailoring at another vocational school, the Mkokotoni learning centre. She set up in business in 2013.

"As soon as we got our diplomas, we formed a group of six people. With the loan we received under the project, we bought sewing machines and opened our premises. The centre has helped me a lot," said Subira.