Interpolated Testing – What is it exactly and what are the benefits?

It seems I may have misunderstood interpolated testing in a recent blog post. I assumed, by definition, that interpolated testing meant that there was switching between new and old learning in the testing of learners (or quizzing).  For example, a typical starter quiz where a teacher would ask questions on previous learning, whilst also assessing the learner understanding on the new.


This understanding was corrected (or confused further?) in a recent lecture on interpolated testing by Dr Philip Higham of the University of Southampton. The talk was fascinating and raised several more questions I wish to consider, particularly in relation to the conflict between desirable difficulties and cognitive load theory (more to follow on this).


The aptly titled ‘PowerPointless’ began with Philip espousing desirable difficulties and the “metacognitive illusions” that exist in learning – massed practice, fluency, lecturer style, testing is bad etc.


Philip then explained a series of experiments that he has been working on with a PhD student. Each of these investigating the impact of slide handouts during lectures. Six lab-based experiments were conducted and pre-recorded lectures given to various groups:

  • Group A – The control group where learners were asked to observe the lecture without taking notes
  • Group B – This group were provided with lecture slides and could annotate these as they wished
  • Group C – This group took notes from the slide for themselves
  • Group D – This group were asked to take notes as if they were for a friend (it was suggested that the notes would be clearer and better organised through doing this)

The various experiments changed variables such as speed of presentation, fluency of presentation and used various topics. Learners were tested immediately after each experiment and then sat a delayed test one week later.


Results consistently revealed that note taking (of any kind) was significantly better than not taking notes and using the slides provided for the lecture (Group A and B). This is significant for all teachers who provide a copy of slides to their learners. Think about how you can encourage learners to take their own notes during sessions – I wrote a blog about the Cornell method a few years back that may be of use for this.


The experiments progressed further, and Group E was added; these individuals were the ‘interpolated testing’ group. This group experienced the lecture in short intervals of around ten minutes before being asked to generate their notes in a retrieval type manner (this is what is referred to as interpolated testing – and the literature that I have read to date typically uses this approach. A short introduction to new learning immediately followed by a retrieval of this new learning). As a side note, is this not just part of what teachers do for formative assessment? (perhaps formative assessment is so effective due to the retrieval aspect rather than feedback?).

The results showed that the retrieval and generation of notes (Group E) had an improved impact on immediate and delayed (1 week) test results compared to other groups.


All groups were then provided with 8 weeks of revision time using the same lecture handouts containing all answers. Following this, they were tested on the material. Results showed no significant difference between those that took their own notes and those that did the interpolated testing. However, the results did show that the quantity of time that learners revised for during the 8 weeks, was significantly lower for those that did the interpolated test (Group E).

These findings are significant:

  • Taking your own notes is highly effective for improving long term retention of information
  • To reduce study time, learners are better off learning via interpolated testing


It is worth noting that much of the literature is positive (see Szpunar et al) on interpolating, specifically for improving long term retention and motivation of learners. The reasons suggested by Davis et al for interpolated testing not being as effective as first thought, is due to:

  1. The learners spending more time thinking about the prior learning and correcting this, over moving to the new learning
  2. The more times that there is switching between old and new learning, the more the task switching effect will occur, thus impeding the new learning

In spite of this, there is a suggestion that ‘test potentiated learning’ (recalling prior knowledge) is actually beneficial to learning and this supports the acquisition of new information. This obviously needs further study, but suggests that teachers need to be mindful of how often they are switching between the delivery of new learning and the retrieval of it during sessions.


*NB. These were some of my notes and inferences from the lecture. Data and information is my interpretation of that which was shared. A huge thanks to Dr Philip Higham for sharing this information and challenging my thinking.

I would like to explore my initial thoughts on interpolated testing a little further, as I expected a delayed retrieval, rather than retrieval immediately after encoding. This allows for greater forgetting which one would think is better… anyway, more thought needed on this. 


Metacognition – How can you do it?

Metacognition is a bit of a buzzword in the education sector, but if I’m honest, I have always been a bit wary of it. I think it’s one of those terms that gets used without much understanding of it. In essence it means ‘thinking about thinking’.


The concept has been broadly and rather loosely defined as ‘any knowledge or cognitive activity that takes as its object, or regulates, any aspect of any cognitive enterprise’ (Flavell, Miller, & Miller, 2002 cited in Waters and Schneider, 2010). This may include, but is not limited to planning how to approach a given learning task, monitoring comprehension, and evaluating progress toward the completion of a task. Arguably many of the above overlap, but both classroom experiments and cognitive science have found metacognitive strategies useful to cement learning and also develop ‘higher order thinking’ within a domain. For example, the Education Endowment Foundation recently found metacognitive strategies to have an effect of +8 months on achievement, though it must be noted that this meta, meta-analysis is unspecific and encompasses a broad range of ‘metacognitive skills’, including less effective strategies such as ‘changing mindset sessions’. Despite this, broadly speaking, 8 months is pretty much a whole school year, so if we use strategies with learners that get them thinking about their thinking, then we may be able to increase achievement.  Below I attempt to provide some clarity on how we might use a range of metacognitive skills in practice, using  Gorrell et al’s (2009 cited in Sart, 2014) list of skills:

Metacognitive skill What this might look like in practice
Evaluation (or criticality of sources or task success). Provide learners with regular opportunity to peer and self-assess against success criteria. Encourage them to ask the following: ‘What am I doing well/how well did I do against success criteria? What can/could I do better? How will I do it better next time?
Monitoring (the assessment of progress through a cognitive task).
Metamemory (a person’s knowledge and awareness of his or her memory usage). Help learners to understand what they already know and how they best remember new information? Do they remember best by creating a mnemonic? By using analogies or metaphors? By taking notes? By self-testing?
Metacomprehension (an awareness of the extent to which a task is understood). Self-explanation – is a comprehension-monitoring approach to learning where the learner explains what they have learnt and how it links to prior learning. In practice, towards the end of a lesson, try asking the learner to write an explanation of their understanding. For example: ‘How do I know that Earth is closer than Mars to the Sun?’
Planning (appropriate structure is assigned to the task). Encourage learners to plan effectively prior to tackling a problem or learning task. Learners could be provided with cue questions such as: What am I supposed to learn from doing this task? What prior knowledge will help me with this task? What should I do first? How much time do I have to complete this?
Schema training (the generation of a cognitive framework to help understand the task). Graphic organisers can be used to help learners visualise their knowledge and understanding.  This visualisation of knowledge and understanding yields high effect-sizes according Marzano. Try using graphic organisers for comparison (Venn diagrams), for classification (Flow charts) for metaphors, or for cause and effect etc.
Transfer (the ability to use strategies learned on one task to complete a different task). The Learning Scientists expertly discuss the notion of transfer in this series of posts (1 and 2). In essence, near transfer (a closely related problem) is easier to achieve than far (a problem without the same prerequisite knowledge). They argue that learners should be supported to:

1.     Recognise that it is a transfer situation (i.e. that they have prior knowledge on the problem/task) – Try  to explicitly inform learners of this when presenting new problems/tasks.

2.     Retrieve the prior knowledge/skills – Try to build in retrieval practice of knowledge and skills through testing, distributed and interleaved practice.

3.     Know how to apply this to the problem/task – Try to provide opportunities for learners to apply their knowledge in different ways.

All of the above lead me to argue the case for scaffolding well when attempting to teach these skills. Each of the strategies are tools that require attention when planning and delivering them to learners. They should be effectively modelled by the teacher before learners are supported with prompts to enable them to become more independent in their ‘thinking about thinking’. Effectual use of these strategies by learners is not something that will happen over night; like anything, it will take time to become proficient in using them. With this in mind, why not pick something that you can introduce to your teaching this forthcoming academic year and see if it has benefit to your learners?