This article first appeared in the Guardian Teacher Blog on Monday 26th March 2012.

Two hundred million pounds is a lot of money to spend every year. It’s the equivalent of five thousand experienced teachers, forty secondary schools, or half a million new computers.

It also happens to be a rather conservative estimate of the amount of money that English schools reportedly spend every year on professional development for teachers (the real value could well be a significant multiple of this).

Any national programme that costs this much money would (or should) come with strings attached. We’d would expect to see a fair old amount of bang for our taxpayer buck. We’d insist that good practice was followed and that bad providers would be hounded out.

So here’s the rub. A fair amount of teacher professional development (also known variously as teacher training, inset, CPD or professional learning) is really bad. I don’t just mean that it’s poor value for money or insufficiently effective – it’s much worse than that. A large swathe of training has no effect whatsoever on pupil outcomes.

In fact, in some cases, teachers come away from irrelevant away-days having made poorly-understood and superficial changes to their teaching that not only make the lessons worse but also leaving them with the impression that they are now better teachers who require less training in future.

Of course you’d expect that this sort of ruse would soon be rumbled and that ineffective provision would be blacklisted, right? Wrong. Many schools still select training and consultancy from a single dominant supplier (often the local authority) or from a folder of assorted fliers that have arrived in the post.

So what does effective professional development look like, and how can schools make good practice stick? Fortunately there have been a raft of reports (e.g. from EPPI and from Ofsted, among many others) that tell us exactly what to look for, and the good news is that great teacher learning is a remarkably similar beast to the great pupil learning.

Philippa Cordingley from the Centre for the Use of Research and Evidence in Education (CUREE) has for twelve years been leading reviews of research about what really makes a difference in CPD for teachers and for their pupils. She has recently evaluated the provision of 75 CPD providers from across the country, and points out that “the international and national evidence is clear – you have to look at both the support that makes a difference and what teachers contribute to their own and each others’ professional learning.

Too much attention in CPD goes into the content of courses and the things CPD providers do to or for teachers. There isn’t nearly enough thought given to ways of making the learning process sustained, stimulating and connected with pupil learning”.

There are some key principles to follow to improve CPD. Firstly, the process of training must start with a clear identification of need. Pupils work better knowing the purpose of learning, and so do we! Teachers need to be able to identify the cohorts that are under-performing, which topics are being taught less effectively, and which skills their pupils are acquiring less fluently.

Once the needs of the pupils have been identified then the effectiveness of the training can be truly judged. This should be a professional judgement using suitable assessments and other data – an investigative process that begins with aspirations for pupils and teacher engagement.

Secondly, once the need is clearly identified, teachers need to access expertise both within school and from outside. Training that fails to take in to account local knowledge and context is likely to be irrelevant, less effective, and poorly received in the same way that teaching that ignores pupil’s own knowledge is ineffective.

External expertise matters to avoid group think and false glass ceilings, and to make sure precious development time is focused on genuinely effective approaches. This expertise needs to be quality-assured and peer-reviewed – there is no point paying good money for training that others have already found lacking, or which fails to live up to its promises.

Thirdly, training has to be sustained. A one-off jolly to the local hotel may be a fun day full of “tricks” to plonk into your lesson plan; let’s be honest, we’ve all got folders full of notes from such courses that we’ve never looked at again.

You wouldn’t expect a pupil to clear up misconceptions, grasp a new theory, and learn how to apply it in one session, and once again the same is absolutely true of teachers. Great training challenges teachers’ practical theories about learning, helps teachers learn and practice new approaches, and sends them away with ideas to experiment with and refine over time.

Once they’ve tried it out they need to access the expertise again on several occasions to build their own confidence, correct misunderstandings, and overcome barriers.

Lastly, professional development has to be active and collaborative. Us teachers are just as prone to tuning out of a “lecture” and contemplating lunch instead as any pupil. This most certainly doesn’t mean yet more A2 posters with coloured pens though!

New ideas need to be put in to practice, observed, discussed and re-evaluated. Teachers need to work in groups to share ideas, breakthroughs and problems. If one person is going off at a tangent then a group is more likely to bring them back to the core principles. Where one person is having a bad week and tempted to discard the new approach in the face of particularly recalcitrant pupils, the others can offer ideas and support.

Reciprocal vulnerability builds teamwork – if I risk looking silly by trying something new and you do the same we won’t want to let each other down so we keep on going in the face of distractions. Peer observations, focused on the new approach and its effect on the target groups of pupils, become a helpful and welcome way of learning rather than part of an imposed accountability system. The external expert should be brought back in or referred to regularly to ensure the new practice is developing in the most effective way.

It’s a big cultural shift, but endless reports and international comparisons have shown us that teacher professional development is one of the cornerstones to improve education for our pupils. Not only does it improve learning but it increases teacher retention and morale and raises the status of the profession.

The Teacher Development Trust, aims to help everyone in education to use these ideas in their own work. One of our tools, GoodCPDGuide, is a national database of CPD where teachers can review each course, consultant, or event for impact on their own practice, and where providers can apply for quality marks from CUREE to prove that their training really works.

We also work closely with CUREE to help support schools and training providers to build better identification of need, to make training more relevant and transformative, and to improve the dissemination and collaboration around new ideas once back in school.

• David Weston is the founder of the Teacher Development Trust andInformed Education, and a Maths and Physics teacher at a secondary school in Hertfordshire. Follow David on Twitter:@TeacherDevTrust and @Informed_Edu.