depth of learning

What the depth of learning is and how it can be used by the teacher

What do you mean by depth of learning?

We really can't measure depth of learning for a layer - but we can find a proxy measure for it - the number of days the app thinks the learner should wait between practising one question and the next from a layer. The longer the learner can remember the deeper the learner's learning on the layer can be said to be.

The depth of learning measure and the formula to decide what the depth of learning should be next after a learner is assessed ✔︎ ~ or * is a work in progress - we continue to look for a more sophisticated formula to calculate what the depth of learning should be next. 

The minimum for the depth of learning is 1 day - this is for pragmatic reasons, maths lessons are in general a minimum of one day apart.

Why is a learner's depth of learning for a layer useful for the teacher?

When a teacher looks at a class' Progress on Topic for a particular topic they can see an indication of the strength of learning for each layer through the colour of each lozenge.

The colour of the lozenge is based on the depth of learning for the layer.

If the teacher wants to see the actual depth of learning held by the app, the teacher can click the Depth of Learning button. Currently we have taken d ≤ 5 days to define fragile and d > 20 days to define mastered.

Why is a learner's depth of learning for a layer useful for the app?

The depth of learning is the minimum length of time that the timely practice cycle wants the learner to wait before practising another question. The wait spaces the learning to improve the learners memory. The wait enables the increasing interval retrieval practice or spaced repetition system (SRS) to work efficiently.

how late is too late?

The learner will probably not entirely forget how to answer questions on the layer after the depth of learning days have elapsed.

The learner rarely practises a question exactly the depth of learning days after the last practice question, because of

  • irregular spaced maths lessons,
  • weekends, holidays,
  • more urgent layers pushing in the queue.

If the learner attempts their practice question

  • 5% late: the learner is likely to remember,
  • up to 25% late: the learner may find it very hard to remember - but may well be able to answer the question independently and accurately,
  • over 50% late: the learner may well need a little re-teaching or a memory jog from the teacher,
  • over 100% late: the learner is likely to have forgotten and need some re-teaching. 

This is why the timely practice app prioritises fragile learning over improving and mastered layers. Fragile layers "push in the queue" so that they are less likely to be practised too late (i.e. after the learner has forgotten what they learned).


The depth of learning is not the length of time until the next question, but the minimum length of time between one practice and the next.