Lesson observations have been an important feature, in the majority of schools, since they became a key part of the Ofsted inspection process when it was founded in 1992. As education has evolved over the past three decades, observations seem to have remained a fixed entity, as they are, for many, deemed the most effective method in identifying the quality of teaching. It is only recently that the validity of the traditional lesson observation is being questioned.

Prior to the September 2005 framework, lesson observations, by Ofsted, were deemed the most accurate way to judge teaching and learning, making up typically 60% of the time of an inspection. As Ofsted was using this indicator measure, so schools aligned to the ‘rules of the game’ and its internal processes of judging teaching used lesson observations using the Ofsted criteria

Observations remained the central method to judge teaching and learning in the September 2005 framework, but they evolved to being used as a piece of evidence to follow up a line of inquiry. Lessons were no longer graded, so the Ofsted observation form no longer graded lessons. Many schools however still continued to grade as they felt the grading of lessons was key in being able to provide them with reliable evidence on the quality of teaching and learning.

There has been, over the years, an increased emphasis on analysing learning over time, whereas the lesson observation only provides a snapshot in time. Lesson observations rely on making a connection between what you are seeing and a belief of the amount of learning that has taken place. It is difficult to quantify how much learning has taken place during a lesson and this judgement is mostly based on a ‘feeling’. While observing the learning, the observer may have a tendency to successfully ‘judge’ lessons based on how the lesson aligns to their own view on quality teaching.

As we are aware, teaching varies from day-to-day and lesson-to-lesson. Sometimes certain approaches work and sometimes they don’t. A successful teacher is able to adapt a lesson to the needs of the pupils and therefore isn’t relying on following a lesson plan ‘word for word’ as they are able to accurately identify the starting point and provide challenge towards the goal. Teaching, therefore, needs to be ‘judged’ over time, using a variety of different sources, to identify the ‘typical/normal’ standard of teaching and learning for a particular member of staff.

Successful schools have developed a toolkit of resources to make an overall judgement of the quality of teaching and learning over time. This has been created to triangulate evidence and includes; 

• Lesson observations
• Learning walks.
• "Drop-ins" 
• Pupil interviews
• Work scrutinies 
• Data analysis

Learning over time aligns with the September 2012 introduction of the teaching standards which were intended to be used for a range of purposes that included assessing the competence of teachers. The standards include;

• Setting high expectations which inspire, motivate and challenge pupils
• Promoting good progress and outcomes by pupils
• Demonstrating good subject and curriculum knowledge
• Planning and teaching well-structured lessons
• Adapting teaching to respond to the strengths and needs of all pupils
• Making accurate and productive use of assessment
• Managing behaviour effectively to ensure a good and safe learning environment 
• Teachers and other staff have consistently high expectations of what each pupil can achieve, including disadvantaged pupils and the most able 

A range of evidence is collected against these standards rather than making a judgment against an individual lesson.