These young people are not here on sufferance. They're here because they and their parents want them to be. Some are floundering in science and maths at school, others are frustrated at their schools' failure to stretch them, and four have been excluded from school and attend the sessions so they don't fall too far behind.
All the children are black, mostly African-Caribbean. The teachers, all specialists in science or maths, are mainly African. It is the Ishango Science Club and is run by the African-Caribbean Network for Science and Technology, an 18-month-old organisation of black scientists that aims to tackle black children's - particularly boys' - lack of achievement in science and maths.
The network was the first body to highlight the problem, when, in 1996, it published statistics from Birmingham Local Education Authority which showed that only 12.4 per cent of black Caribbean boys received Grades A to C in gcse science, while the corresponding figure for white boys was 36.9 per cent.
A 1996 review of ethnic minority achievemen t by the Office for Standards in Education backed these findings on a national scale. Something was wrong, and Liz Rasekoala, a Nigerian-born chemical engineer living in Manchester, decided to take action to address the problem.
She set up the Network and last February opened the Ishango Science Club, named after an ancient east African bone covered in mathematical carvings. supported by Manchester LEA, the club now has 172 children on its books. It is open one afternoon after school mid-week and every Saturday. Another club in Toxteth, Liverpool, has 150 children and runs after-hours sessions six days a week. It operates from the Parents School Partnership Centre, with students using the facilities of Hope University College. Plans are also being made to establish groups in Nottingham and Birmingham.
The children have little doubt that Ishango is answering real and pressing needs. Jennifer, 11, says: "If we don't learn things at school, we learn them here - like mental arithmetic. You get to do more things here, instead of just listening to a teacher rabbiting on." Stephen, 13, adds: "You don't get yelled at here. They don't treat you like you're in nursery."
For 11-year-old Thembi, the club has made a world of difference. "My mum thought it would help me at school," she says. "I was in Zimbabwe for three years and fell behind with my schooling. Now I'm ahead in my class."
Ms Rasekoala believes the key to the students' enthusiasm and progress lies in the way the material is delivered. "Africans are interactive people and that's how we teach. The children all know they'll have to answer questions and will be asked to come up to the board. Children don't just sit here and listen. They are doing things all the time."
Staff use British Association Youth Section experiments. "They're kind of Blue Peterish," admits Ms Rasekoala, "but it's getting them to make sense of science by being creative."
James Usman, a chemistry PhD and secondary school teacher, has 14 students participating in an experiment illustrating Hook's Law, showing how different materials have different elastication points. "It's old physics," he explains. "They don't learn it any more in science. But exams refer to it and students are asked to prove it."
And his class is proving it, with varying-sized bags of sand and a nail-bitingly flimsy rubber band. The children, uniformly attired in Nike and Kappa gear, are desperate to be chosen as volunteers.
Behind the scenes, too, there is a wealth of activity. All the club's specialist tutors have done training and induction with the LEA's science and maths advisors, who were "loaned out" to the project for two-and-a-half days.
Tutors are big on assessment, too. Each child goes through preliminary standard science and maths tests, as a baseline assessment. Year 10s are also given a GCSE foundation level paper. After that, they are all tested on a monthly basis to check which areas need reinforcement.
Alongside the straight teaching, children are taken on outings to industrial sites of scientific interest, to show the variety of jobs in science and engineering - and often, how few, if any, black people have those jobs. "When we went to NorthWest Water, we didn't see one black person," recalls Ms Rasekoala. "For the children, it really illustrated what the club's all about."
Having black teachers deliver parts of the curriculum traditionally taught by white professionals also brings an aspirational element, by providing rare but vital role models.
The Ishango project is working with eight secondary and eight primary schools in Manchester, trying to target children from Year 5 to GCSE level who may need extra help. Ms Rasekoala has been using the schools to pass on information about the project to parents. She believes it has served as a catalyst for the schools' own efforts. "Two of the schools have organised meetings on achievement for African-Caribbean parents since we've been here," she says. "It is opening up a dialogue with the community, sometimes for the first time, on what schools can do to help black children succeed. "
But the group recognises it has a long way to go before schools shift practices, let alone attitudes, far enough to make sure all children get the help they need.
A mother of one Ishango Club student says: "My daughter is being typecast in her science and maths class because she doesn't have confidence in those subjects. So her teachers are just letting her drift, like they don't believe she's up to it. But she is, and she's showing it here, where the structure gives her the stimulation and attention she needs."
For more details about theIshango clubs, contact Elizabeth Rasekoala, African-Caribbean Network for Science and Technology, Ishango House, 447 Chester Road, Manchester M16 9HA
Tel: 0161 877 1480