How To Use Diagnostic Assessment To Inform Your Teaching

Diagnostic assessment is a key tool in KS2 Maths teaching, but one that can be difficult to know how to do effectively. Candida Crawford, primary school teacher and lead on Curriculum Design for Third Space Learning, shares her insights on how to make it work best for you. 

Assessment has always been crucial to how we teach Maths. With an ever-growing curriculum, times tables tests on the horizon and more, the time we spend teaching pupils needs to be as effective as possible.

We need to know their gaps, attempt to teach to those gaps, and then check that pupils have retained their knowledge. Plus, as pupils move up to your class each year, getting to grips with their existing knowledge (without spending forever testing them) can be tricky.

As KS2 Maths intervention providers, we spend one hour a week with over 7,000 pupils. In that hour, we have to know what progress each pupil has made in order to determine what is taught in the following week, and to make sure that our wonderful schools who trust us with their pupils have total insight into how their money is being spent, and for what impact.

Over the years, we’ve learnt how to strike a balance between assessing thoroughly enough that we understand pupils’ gaps, and being light-touch enough that it doesn’t eat into crucial learning time.

Here’s what we’ve learnt about how to meaningfully assess primary Maths pupils, without spending too much time testing.

Assess KS2 Early: Initial Diagnostic Assessment

First up, we always assess pupils at the start of their term with us. This is a key part of all our programmes, and it has two main purposes.

Firstly, to inform the teaching; and, secondly, together with a post-session assessment, it helps to measure the impact of lessons on pupils.

In your school: Like many you may be unwilling (or indeed find it unnecessary) to do a pre-test at the start of every term, but we would strongly recommend it for at least the start or the year.

This helps track real progress, as it provides a comparative baseline assessment based on a pupil’s position as they’ve returned to school after the long summer holidays. Clare Sealy’s blog post on How to Beat Summer Brain Drain is an essential read on this point. 

KS2 SATs Assessment Procedure

Before we start teaching any lessons to the Year 6 pupils on our KS2 SATs programme, we ask them two types of questions on each topic: calculation problems and worded problems.

These help us see whether a pupil needs to spend time learning a procedure or concept and, if they are able to use it, whether they can apply it to a problem.

From this, we can see how they’re doing in each area on the plan sessions page.

Example answers and insight from the KS2 maths diagnostic assessment for a pupil
Example answers and insight from the KS2 maths diagnostic assessment for a pupil


Example lesson list showing degree to which a pupil has mastered one of the key Maths revision concepts
Example lesson list showing degree to which a pupil has mastered one of the key Maths revision concepts
Diagnostic Programme Assessment Procedure

For pupils on our Year 3 to 4 Diagnostic Keep Up Maths Programme it is a bit different. We will ask the teacher to choose limited areas of the curriculum for the pupils to focus on, so that we’re able to ask more questions on a specific topic.

This helps us to really drill down into their specific misconceptions and be able to automatically select lessons which the pupil’s class teacher can then over ride if required.

Thousands Of Diagnostic Maths Questions Available

For schools using our 1-to-1 Maths intervention, we have written thousands and thousands of questions to be used for assessment! And they’re all carefully aligned to the curriculum and the appropriate year group.

We chose to use a multiple choice format, and for each question we created one correct answer and three distractors.

A word on distractors. In our experience these are highly important; they’re not just random wrong answers but are designed to be an answer a pupil could potentially get to based on a specific misconception.

image 1 is working towards 12 hour clock and 24 hour clock
An example of a diagnostic assessment question on our 1-to-1 Maths platform: aimed at pupils working towards, focusing on 12 hour clock and 24 hour clock
image 2 is working at 3d solids in 2d representations
An example of a diagnostic assessment question on our 1-to-1 Maths platform: aimed at pupils working at, focusing on 3D solids in 2D representations
Image 3 is extension missing angles
An example of a diagnostic assessment question on our 1-to-1 Maths platform: aimed at extending pupils working on missing angles

In your school: When you conduct your own diagnostic assessment at school, make sure that any tool or questions you use include distractors too so you know why a pupil has made a mistake.

On our platform, all the pupils’ answers feed into a unique algorithm which either suggests lessons on the SATs programme or helps you pick lessons on the diagnostic programme that are most relevant for you.

For your teaching, we advise that you teach to the results you have found. This will save you time and help you target the areas that pupils need help with the most.

Where To Find Quality Assessment Materials For KS2

As well as the thousands of questions on our platform, we have also created a series of free KS2 diagnostic quizzes on seven key topics: from addition and subtraction, to fractions decimals and percentages.

Each quiz contains multiple choice questions specifically created to identify precise misconceptions, and includes mark schemes to help plug gaps and inform planning.

Download the Year 6 Diagnostic Maths Quizzes here.

Download the Year 5 Diagnostic Maths Quizzes here.

Low Stakes, Frequent Testing Is Key To Great Assessment

On all our intervention programmes, the initial baseline test is topped up with assessment throughout the term.

This comes in the form of a couple of questions after their 1-to-1 lesson each week. Using these answers we can continuously diagnose gaps, and our tutors will always use a question the pupil got wrong in the previous week to start off the next lesson.

In your school: In your own teaching, you can use individual questions taken from our free diagnostic quizzes every single day to find out how well pupils are taking on what you’re teaching them. Remember that a correct answer just after the topic has been taught doesn’t necessarily mean a topic has been learned!

Online Testing And Technology Over Tutor Assessment

Given that every pupil has the same tutor over their term or 14 week programme with us, you may wonder why we don’t make more use of tutor assessment.

There are two main benefits to using our own question bank instead:

First, an online assessment gives consistency. We have over 200 tutors, who all might assess slightly differently. By using these online questions we can get a more independent and objective view of where the pupils are at.

Tutors will still use their own judgment on top of our independent assessment during a lesson as any teacher would – they might accelerate through material if they see it’s too easy, for example.

Second, an online assessment give us data we can look at and learn from. We set ourselves a strict list of standards we expect all our tutors to meet in lessons and the data we gather from our online assessments helps us see if tutors are consistently meeting these.

If a lesson takes too long to complete, our numbers will show it and we’ll investigate qualitatively.  Why? What’s the question pupils keep getting wrong? Is something wrong with the distractors? Is the question too wordy? Or is the question uncovering a very common misconception that we could use to inform and better improve the lessons and the teaching? 

This level of actionable insight at scale just wouldn’t be possible to moderate from all our tutors.

In your school: We only have an hour a week with your pupils. It’s amazing what we can achieve in that time, but it’s not the same as the day-in day-out contact and knowledge that a class teacher has about their pupils. We are certainly not advocating you move to a purely online / paper assessment process for your own pupils; it just needs to be part of the mix together with teacher judgement.

Beyond Subject Knowledge: Confidence And Attitude

There are more things to assess than a pupils’ subject knowledge.

At Third Space, one thing we’re really excited to be working on is measuring pupil mindset and confidence.

Many of our client teachers have told us that the 1-to-1 sessions make a big difference on pupils’ confidence, engagement and willingness to get involved in lessons. So, we worked hard to create a system to measure this impact. You can learn more about how we measure pupil attitude and mindset in maths here.

The impact mindset can have on results: a quote from a teacher using Third Space Learning
The impact mindset can have on results: a quote from a teacher using Third Space Learning

In your school: Don’t dismiss the power of Growth Mindset to transform a pupil’s confidence and results in KS2 Maths. We have seen time and time again that engagement and willingness can have a big impact on whether or not a pupil secures and retains any taught knowledge.

The Challenges Of KS2 Maths Assessment

The main challenge most schools face when assessing is balancing the need for assessment with giving pupils and schools the best experience – mainly we don’t want to over-assess or take up too much time. This is something we experience as well!

We could do a really in-depth testing of pupils after every lesson, but we don’t want to exhaust pupils or make them disengage  – we know pupils are already tested a lot in school… it’s a balancing act!

Next Steps For Third Space Learning’s Diagnostic Assessment

After years of practice, we now feel we’ve got this balancing act right by testing in a low stakes, high frequency way and making sure we get as much value out of each assessment as possible.

Our next steps, as we have increasingly large data sets on pupils’ responses to the tests (7000 pupils answering our questions every term)  are:

a) to refine the questions we ask to become even more accurate predictors of gaps

b) provide an even more engaging test environment for the pupils we teach so it’s never seen as a chore

c) work on ever more reliable metrics for changes in attitude.


To find out more about how we assess pupils, or how our 1-to-1 Maths interventions can double progress in your school: book a demo of our maths interventions here.


David Leighton
David Leighton
Third Space Learning
Content Team
A former secondary teacher, David writes blog posts and Maths resources as part of the content team.
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