It looks innocuous enough, but the two-storey building tucked behind a health centre is in the vanguard of a new approach to teaching maths.
From this former swimming baths, some of the UK's leading lights in maths, physics and engineering are expected to emerge over the coming years.
This is the King's College London Mathematics School in Lambeth, south London. Run by the elite Russell Group university, it is one of the first of what is promised to be a nationwide network of specialist centres of excellence for 16- to 19-year-olds.
A few weeks into the school's opening term, the students making up its first intake are just like any other 16-year-olds excited by their move to post-compulsory education - albeit ones who have to sign a waiting list to join the robotics club.
"Maths is something I've been good at since I was a kid," said Ike Osakwe, 16, who joined from St Andrews High School in Croydon. "Other subjects I struggle with, but maths doesn't feel like working. It feels more like I'm expanding my knowledge."
He is not the only one to think that way; the school attracted 130 applications for 60 places. As well as GCSE A grades in maths and physics, applicants had to pass a test and two interviews. Almost half the students are girls and nearly all come from state schools.
The idea is to grab pupils with the potential to get into top universities and give them a further boost by providing links to university maths departments, while also devising tailored projects to improve their skills. Students at the Lambeth school, for example, take A-levels in maths, further maths and physics, with an optional AS in computing in their first year and an extended project qualification in their second.
But as well as helping their students, these maths free schools are expected to help us all. Announcing their creation in 2011, chancellor George Osborne said they would "give our most talented young mathematicians the chance to flourish" and "produce more of the engineering and science graduates so important for our longer term success".
The schools are loosely based on the Russian model of the Kolmogorov Physics and Mathematics School, part of Moscow State University. This was founded in 1963 by the renowned mathematician Andrei Kolmogorov, who also taught there.
But they have been slow to get off the ground. The government's original aim was to create a network of about a dozen schools, sponsored by universities, but so far only two have opened: King's in London and Exeter Mathematics School.
A promise by former education minister Elizabeth Truss to fast track new maths schools has produced just one extra applicant, from the University of Central Lancashire.
However, education secretary Nicky Morgan is confident that this is just the beginning. Speaking to TES after the official opening of the King's school, she said: "I think that some [universities] are clearly waiting to see how the King's and Exeter schools go. Clearly there is a huge amount of effort required, but I think King's will be enormously successful, and I am hoping they will be leading by example."
King's College London Mathematics School is light and airy. A large spiral staircase leads to an open area containing yellow three-sided pods covered in equations. This is where the students do extracurricular problem-solving in small groups. Once a week, PhD students from King's College London visit to go through their workings with them.
"I am gobsmacked how this can happen in such a short period of time," said headteacher Dan Abramson. "I have been bowled over by the goodwill, energy and sheer determination of people who made sure it happened."
The Exeter maths school, where 34 students started this September, has the added responsibility of taking care of boarders. The school serves a 175-mile stretch from Cornwall to Dorset, and 11 students are staying in the school's staffed accommodation from Monday to Thursday.
"It's a wonderful opportunity for them," said headteacher Kerry Burnham. "It reflects what we're doing in the school - offering a stepping stone to university."
Exeter Mathematics School is linked to both Exeter University and Exeter College, giving students access to the latter's music, sport and other clubs. King's, too, is keen to broaden students' horizons. In addition to maths and physics, they must learn a language and will be studying the history of ideas.
Joselyn Joanes, 16, who moved to King's from La Sainte Union in Highgate, North London, said: "If you want to be the best at what you do, this is the place to do it. I don't particularly like languages, but I like maths so much that I will suffer learning a language for it."
Go forth and multiply
But although the maths schools have received serious political backing, not everyone is convinced that their modest number will make a significant difference to promoting the subject.
"I'm very supportive of more people doing more maths, but even if you have 12 schools, you are really scratching the surface," said Andrew Noyes, head of the school of education at Nottingham University and a former maths teacher.
"These kinds of policy experiments are very nice and they're beneficial for a certain number of young people, but they're relatively cheap compared with providing high-quality maths education at every stage in every school," added Professor Noyes, who is also deputy chair of the independent Advisory Committee on Mathematics Education.
The schools' success will inevitably be judged on the fortunes of its students, including the proportion that go on to top universities. But they have a wider remit, too, which includes sharing their resources and setting up networks and teacher training links with other schools.
The project is also for the long term. Setting up a school takes time but creating world-class scientists is harder still. After all, what if some of the students fancy doing something else once they leave?
"People sometimes do have changes of heart," Exeter's Ms Burnham said. "It's not a problem. I think we are giving them an experience which will really enrich, stretch and challenge them. They will come out feeling confident as mathematicians and scientists.
"I'm sure some might decide later to do something completely different. That is not a failure. It's not our job to push them into Oxbridge [but] to equip them to be able to thrive at university, and find a career that's right for them and that they love."
The number of candidates sitting A-level maths:
2004: 52,788 - 6.9 per cent of total entries; third most popular subject after English and general studies
2007: 60,093 - 7.5 per cent of total entries; second most popular subject after English
2010: 77,001 - 9 per cent of total entries; second most popular subject after English
2014: 88,816 - 10.6 per cent of total entries; most popular subject