The latest issue of the TES contains a good article on differentiation by Mike Gershon. There has also been a spate of articles about it online recently, such as this one from the Guardian by Rachael Stevens, and this one by @headguruteacher. Here is a summary of a few key points.
DON’T assume that differentiation is just about providing support for the less able or extension for the more able. DO try to ensure that ALL pupils will find the lesson challenging – as the old saying goes, nothing worth having ever comes easy.
DON’T assume that differentiation is something that you have to plan into every part of your lesson. DO take note of how the students are getting on, and be prepared to clarify tasks, give examples, model a task, ask more probing questions, etc.
DON’T assume that the easiest way to differentiate is to group pupils according to ability. This may sometimes be true, but DO consider extending pupils who are succeeding by asking them to support those who aren’t.
DON’T assume that the best way to differentiate is to offer three different versions of the same task. DO expect all pupils to complete several tasks which vary in nature: this means that each can let their strengths come to the fore at different stages in the learning process.
DON’T direct closed questions at the less able and open questions as the more able. DO give all pupils the opportunity to answer all questions. This may mean you need to allow more time to some than to than others, or that you need to break the question down more for some than for others.
For some good practical ideas on how to deliver lessons which are both accessible and challenging, check out this resource posted on the TES website.