I stared at my Year 11 class, baffled. These students had achieved so well in Year 10 English, but they had apparently already forgotten everything I’d taught them.

A quick recap quiz on Of Mice and Men - a text that they had scored high marks on in an assessment around 12 months earlier - revealed embarrassing knowledge gaps, including character names and basic plot points.

What had gone wrong? At first, I couldn’t work it out. But then I came across a 2013 study by Dunlosky et al (“Improving students’ learning with effective learning techniques”, Psychological Science in the Public Interest, bit.ly/Dunlosky). This helped me to realise that a vital ingredient was missing from my teaching: distributed practice .

Also known as “spaced practice”, this means distributing learning of a topic over time, rather than studying it all in one go (known as “massed practice” ). For example, a student might spread out five hours of revision on electrical circuits over two weeks, rather than cramming for the same amount of time the night before the exam.

What does the research say about distributed practice? The team evaluated the effectiveness of 10 popular learning strategies. Assigning distributed practice a “high utility” level, they argued that spacing out practice was far more effective than massed practice when revisiting previously studied material.

The researchers also looked into the optimal lengths of time between practice sessions. Using the example of a study where students learned Spanish translations, they found significant benefits when distributed practice involved a month-long “lag”. A gap of this length produced greater benefits than a shorter lag of one day.

The team found that this holds true for children of all ages; they reference studies in which nursery children were able to recall more pictures after longer lags.

And there is a reason for this. They explain that remembering recently studied material feels easy, which misleads students into thinking they understand it better than they actually do. By contrast, repeating learning after a 30-day lag triggers memories of the initial learning experience, supporting the retrieval of information in the future.

However, the study points out that most schemes of learning and textbooks don’t encourage spaced practice and instead “lump related material together and do not review previously covered material”.

Getting quizzical

If I wanted to ensure that the learning would stick, I needed a new approach. So, I applied the research in three main ways. First, I used starter activities as opportunities to test students’ retention of prior learning.

Second, I cut right back on setting “extra” tasks for homework and instead ensured that students used their home learning time to revise topics we had covered a week, a month, or three months previously. As the research states: “Students will not necessarily engage in distributed study unless the situation forces them to do so.”

Finally, I used low-stakes quizzes in each lesson to test whether learners had retained knowledge and done their homework.

The positive effects, however, did not come right away. Initially, some students lost their confidence, as my new quizzing regime forced them to acknowledge the hefty holes in their knowledge. High-flyers had to come to terms with low scores.

And they weren’t the only ones struggling. The changes took some time for me to adapt to as well. Quizzes that I thought might be too easy turned out to be way too hard - I continued to overestimate what students had transferred to their long-term memories. While my starter activities had previously offered interesting introductions to new topics, using hooks to draw learners in, I now worried that students would become disorientated switching between topics; that they would find my lessons tedious and repetitive. I worried that I’d get bored, too, missing the novelty of moving on to the next thing and consigning the previous topic to history until it was time to revise.

Yet, after a few bumpy weeks of transition, things started to turn around: my students’ quiz scores began to soar. From a starting point of an average of around 30 per cent, their marks now increased to an average of between 70 and 80 per cent.

At the same time, students’ confidence grew and this burst of affirmation proved more sustaining than the novelty of constantly “learning” new stuff; they could see that they were making daily progress. And, as an added bonus, they began to make greater links between hitherto unrelated units. They started to notice overarching themes and to apply critical ideas to different topics.

Parents also noticed the difference. Several told me that the new regime had changed their child’s attitude to English lessons; it turned out that knowledge retention was far more rewarding than innovative starters.

As if that wasn’t enough, I found that my own workload dropped, too. I could slip in quizzes at any point and no longer needed to come up with creative ways to introduce new ideas.

This, of course, was a major bonus. But best of all was watching students who were hard-working and motivated enjoy the satisfaction of successful recall being cemented over time.

Mark Roberts is an assistant headteacher in the South West of England

This article originally appeared in the 1 February 2019 issue under the headline “Total recall is all about the ‘lag’”