"But the real difference is in the classroom, in the way students engage with things now," he says. "Instead of it being done to them, they are now part of the process."
Mayfield is a large 11-18 comprehensive in Ilford, north east London. Mr Rehling says that when he took over as head four years ago, the school had been coasting. "My impression when I first came here was that not enough children were as engaged as they could be," he says. "So it was a case of trying to put them in the driving seat, in taking charge of their learning and being part of their own education."
Its last Ofsted inspection declared it a good school, with pupils making sound progress by the end of Year 9 and impressive progress by Year 11. The inspection found good attitudes to learning and behaviour.
Mr Rehling had the advantage of having been a deputy head in Redbridge, so he already had contacts within the education authority and with other schools.
The partnership allowed teachers from different schools to work together and try out new approaches in the classroom. Networks were also built internally - staff were put into groups of three to observe each other's teaching.
"Some of the feedback we had from that was phenomenal," he says. "I remember distinctly one teacher who had been teaching for 25 years coming into me and saying he had just been into an NQT's lesson and said 'It was just incredible - I learned so much'."
Teachers also visited each others schools and held seminars. "Collaboration is thriving in Redbridge," says Mr Rehling. "I think there's a real commitment to working together and creating change for children.
"My dread is that we go back to schools being in competition with each other, not sharing methodologies and not talking to each other as professionals.
"These are the children of east London - they all deserve the best. It's not just about individual schools."