Developing whole school assessment

Using assessment data as a starting point

The data generated by assessment can be an invaluable starting point to inform teaching, but it is important to be clear about the intended purpose of different assessments and the uses of the data that they generate.

As an example, many secondary schools use Computer Adaptive Tests (CATs) early in Year 7 to identify which pupils might need extra teaching for specific areas of the curriculum. Also, schools are increasingly accessing the question-level data generated by Year 6 Key Stage 2 SATS for diagnostic purposes. The data can be used to inform important decisions, such as which interventions are required for different pupils. Assessment data used in this way can be valuable information to support learning.

The video below provides an overview of the elements of great school assessment. 

What makes a great assessment?

The assessment process and the data it generates should be valid (they measure that which they were intended to measure and data are appropriate for the interpretations intended to be made from them) and reliable (consistent over time) for the purpose intended: a poor-quality assessment may give misleading results and lead to poor-quality decisions.

By using high-quality data efficiently as a tool to help inform practices in school three positive consequences can occur:

  • Senior leaders and their teachers make conscious decisions about the specific uses of each piece of assessment data they will collect. This enables productive conversations about ensuring these are appropriate and useful for the intended purposes.
  • Teachers and senior leaders consider the opportunity costs of assessment. They recognise that the time and effort spent on assessment must be as valuable – if not more so – than other ‘opportunities’ (such as more teaching time) which could have been taken up.
  • Assessment data informs decisions about teaching and learning. Lessons and interventions are planned proactively in response to purposeful assessments.

Validity & Reliability

In the context of assessment:

Validity is understood as the degree to which an assessment measures that which it intends to measure, and the suitability of the data generated for the interpretations intended to be drawn from them.

Reliability is understood as the consistency with which an assessment performs its function.

For example, a valid assessment of current maths ability, will actually measure how well that individual is currently doing in maths (as opposed to providing a long mathematics word problem, for instance, which requires a certain level of reading skill to understand it). A reliable assessment will do this consistently over multiple instances of the assessment. If the same child took the same assessment twice in the same day, for example, the outcome would be broadly similar.

Good practice use of the terms validity and reliability is to follow them with the phrase ‘…for the purpose of X’. For instance, teachers and school leaders might talk about ‘the validity of the Year 6 maths exam for the purpose of assessing pupils’ progress in maths during Year 6’.

Understanding what is meant by the terms validity and reliability is one thing, but identifying them as values of specific assessments can be a challenging task. The range of assessments used in any one school (standardised tests, past papers, teacher assessments) generally comprises differing degrees of validity and reliability. Assessments which provide evidence about their validity and reliability (as many commercially-available assessments do) are not necessarily better quality tests than those created by teachers in school, but more is understood about these important aspects and, consequently, judging their quality is more straightforward.

When it comes to making decisions about pupil understanding and progress based on assessment data, the greater the validity and reliability of an assessment, the greater the trust that can be placed in the data it generates.


Identify the assessments used in school which need to be highly-reliable and valid measures of that which is being assessed (generally these are the high-stakes assessments with important decisions attached to them). How valid and reliable they are for the purposes to which they are put?