It is regarded as one of the most important parts of teachers' work and has been referred to in a variety of ways, from mixed-ability teaching to personalised learning. But the teaching approach now most widely referred to as "differentiation" can still be a difficult one for teachers to grasp.
In his best-selling teacher-training manual Teaching Today: a practical guide, Geoff Petty describes it as "the process by which differences between learners are accommodated so that all students in a group have the best possible chance of learning".
Peter Anstee, an English teacher and author of the Differentiation Pocketbook, says that it is about adapting teaching and learning styles to suit the whole class, groups or individuals.
Both agree that the lack of a consistent and clearly defined description of differentiation has led to confusion among teachers, which has caused the idea to be widely misunderstood and misinterpreted.
Petty says that the traditional term "mixed-ability teaching" was unsuitable because teachers realised it was not just ability that could be mixed and that they had to cope with a range of differences among their pupils - such as age, gender, learning style, motivation, prior learning and experience - as well as specific learning difficulties such as dyslexia.
But the accepted replacement term, "differentiation", is less vivid and less readily understood. "Some believe that it is something added on to normal teaching and that it just requires a few discrete extra activities in the lesson," Petty says. "In fact, differentiation permeates everything a good teacher does, and it is often impossible to point to a discrete event that achieves it."
The confusion and lack of clear information on the subject inspired Anstee, an English teacher at Brentwood County High School in Essex, to write his first book, which has become one of Teachers' Pocketbooks' biggest sellers since it was first published last year.
"I'm particularly interested in teaching and learning, but when I have been running training courses and Inset days, I've noticed there's not a lot of advice and guidance available on differentiation," he says. "I've gathered a lot of information on it myself and I've been experimenting with different methods in the classroom."
Anstee says that differentiation can be a "daunting" prospect for a teacher because it can involve planning several different lessons. The key, he says, is to give students choice.
"If students are given choice, they challenge themselves more than teachers do," he explains. "A lot of teachers shy away from it, or give too much choice and it goes wrong. I have developed a staged approach in which I start small and build up from there."
He believes some differentiation strategies have done more harm than good, and says that teachers must get away from the idea of defining the ability of individual students and grouping them as such, as it soon becomes a "self-fulfilling prophecy".
"It needs a more subtle view," he says. "You need to understand why you are differentiating - to create routes through learning that allow all students to achieve and progress. It's not just about setting up a series of different activities, but planning learning that is generated from students' needs.
"In my class, we use assessment-led learning, where assessment informs the next piece of learning."
The Kagan approach
One differentiation strategy that is growing in popularity is the Kagan method of teaching. Developed in the US, Kagan is a cooperative learning strategy that claims to improve pupil achievement and social skills.
Michelle Rathor, an English teacher at Our Lady's RC High School in Blackley, Manchester, came across the concept while training to be an advanced skills teacher four years ago.
She was looking for an effective differentiation technique to improve results in her mixed-ability classes and had heard about a nearby school, Fallibroome High (now Academy) in Macclesfield, which had turned its results around using Kagan methods. So she attended a training course.
"Kagan promotes whole-class engagement and enjoyment," she says. "Pupils rely on each other and every child has a part to play in every task."
In Kagan terminology, children are described as either "hogs" or "logs". "Hogs" are the pupils who will always answer questions and take part in learning activities, while "logs" sit silently and hope the teacher overlooks them.
Using one of the programme's 225 structures can dramatically increase classroom participation, it is claimed. Rathor often uses a structure known as "rally robin".
"Say, for example, we were reading a text and I asked a question to test what they could remember," she explains. "Usually, only half of the class would put their hands up to answer and maybe 10 of those would actually interact. With 'rally robin', pupils partner up and rely on each other for the answers. It reinforces the learning and everyone has had a go."
During activities, Rathor often splits her classes into mixed-ability groups of four and assigns each pupil an individual role, which is rotated after each turn.
She says that it is important not only to know each pupil's ability, but to let them know it too, so they are aware what their targets are.
"We have never had a situation where we have had pupils looked down on by others," she says. "It doesn't matter what level they are working at, as long as they are pushing themselves. As far as I'm concerned, if you are making progress, you are doing a good job."
Rathor is now a certified Kagan trainer and has embedded the methodology in all English classes.
"The difference has been unbelievable," she says. "When I started in 2007-08, the overall pass rate for English GCSE was 33 per cent. Last year, it was 70 per cent. I can't put that solely down to Kagan, but it has had a huge impact."
When differentiation goes wrong
Petty believes that, although differentiation strategies like Kagan that use whole-class interactive teaching and cooperative learning techniques can have a positive impact, the focus on differentiation has more often been unhelpful.
He says that it has been interpreted in ways that have actually set back attempts to narrow the achievement gap between the weakest and most able students.
"It is a floundering concept that would be better dropped," he says. "One of the problems is that it has been interpreted to mean you treat students differently in the classroom, that you have low expectations of the weakest students and set them very simple tasks. The idea that every student should be taught in an individual way is a disaster; it doesn't work."
This is differentiation by task, which Petty argues is only rarely effective. Instead, he says an easier and more effective strategy is differentiation by outcome, where students are set the same tasks, which they can all attempt and will stretch the most able.
But he says: "In many respects, I wish people hadn't thought the term up and we would focus instead on the methods we know achieve the most and benefit the weaker learner. So many methods work better, such as embedded formative assessment and interactive questioning methods."
Differentiation Pocketbook by Peter Anstee is available from www.teacherspocketbooks.co.uk
Teaching Today: a practical guide by Geoff Petty is available from www.geoffpetty.com
More details about Kagan workshops can be found at www.kagan-uk.co.uk
Fan-N-Pick - In a group of four pupils, one fans a pack of question cards. The second picks a card and reads the question. The third answers. The fourth checks whether the answer is right and either praises the respondent or coaches them in the right answer. Roles rotate after each turn. This approach promotes teamwork, thinking skills and communication.
Showdown - One pupil in a group of four is named the captain, and he or she reads a question card aloud. The others write the answer on slips of paper or boards and keep them secret. When the teacher gives the showdown signal, all pupils reveal their answers. If all are correct, the team gets full points. If not, they coach each other. Roles rotate after each turn.
CATERING FOR DIFFERENCES
There are three generally accepted categories of differentiation.
By task, which involves setting different activities for pupils of different abilities.
By support, which means giving more help to certain pupils within the group.
By outcome, which involves setting open-ended tasks and allowing pupil response at different levels.
A good teacher will ideally use all three to accommodate different learning styles in the classroom.
Tips from Peter Anstee's Differentiation Pocketbook
Student choice. Start with small levels first, then build up.
Questioning. Target specific questions at specific students.
Group work. Ensure students have specific roles they are accountable for. Vary them for different students and rotate responsibilities.
Assessment. Give students the opportunity to approach tasks in a different way that would better suit their abilities. For example, instead of an essay, can they prepare a presentation, write a news report or create a podcast?