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Error-spotting exercise



An error-spotting exercise is an exercise typically used for diagnostic purposes (though it may sometimes also be used for evaluative purposes) in learning. The exercise typically involves being presented with a short piece of text (instead of text, there could be an image, a flow of mathematical steps, an audio, a video, etc.). The goal of the exercise is:

  • Error detection: Identify the errors, and the root cause of the error (i.e., not just the point where the failure is obvious, but the point where the first wrong steps were taken)
  • Error correction: Identify possible ways to fix the error and obtain something completely correct.

The reason why error-spotting exercises are better suited for diagnosis than for assessment is that it is hard to create a clear grading rubric for error-spotting.


Parameters relevant to error-spotting exercises

  • Prior knowledge about nature of errors: An error-spotting exercise may specify the type of error. For instance, it may specify that there is a computational error, so that the reader can concentrate on the computations and relax when reading the remaining material. An error-spotting exercise may also refuse to specify the nature of error, so that the person attempting it needs to critically examine every clause.
  • Prior knowledge about number of errors: An error-spotting exercise may specify that there is only one error, or it may specify that there is at least one error. The latter form of error-spotting exercise is more challenging and educative, because it means that even after finding one error, the reader still needs to continue critical examination. For error-spotting exercises with multiple errors, easy errors may be used as red herrings to divert attention away from the more serious errors.
  • Distinction between initial point of error and stage at which the error becomes obvious: In some cases, an error-spotting exercise may make the erroneous assumption at a certain point in the exercise, but the error there is very difficult to catch. However, at some later stage, as the implications of the assumption propagate, it becomes more and more obvious that something was done wrong. In this case, we can distinguish between simply noticing the final stage where the erroneous assumption has propagated far enough for a visible contradiction, and successfully diagnosing the stage where the original erroneous assumption was made. This debugging or troubleshooting component to the exercise has significant learning value.

Real-world contexts that error-spotting exercises are similar to

In many professions, a lot of the day-to-day work of the profession has similarity to error-spotting exercises. Examples include:

  • Review of one's own work
  • Peer review (such as code review in software engineering, academic peer review)
  • Debugging of problems with systems (such as code debugging in software engineering)

Unlike error-spotting exercises that are designed for pedagogical purposes, real-world contexts may have much more uneven distributions of errors (in fact, some things being reviewed may have no errors).


  • Error-spotting exercises require people to critically pay attention to every aspect of the material presented. The method is therefore a highly active form of recall relative to methods such as quiz and recall. They also overcome the psychological problem where people simply read and superficially seem to agree with what they are reading.
  • Error-spotting exercises can pack more punch per item, because the person reading needs to check a large number of different facets of the statement in the process of error discovery.
  • Error-spotting exercises are great for tackling specific learner misconceptions.
  • Correctly cracking an error-spotting exercise gives a greater aha moment and stronger consolidation of ideas, invoking epistemic emotions of confusion and surprise in service of learning.


  • Because of the inherently high difficulty of error-spotting exercises, they are suitable only at later stages of review, not at the initial stage of learning, where one is still in the process of acquiring basic knowledge.
  • Error-spotting exercises are generally unsuitable for assessment because it is hard to design a consistent grading rubric around them. Thus, even though they are good for diagnosis, people who prefer their diagnosis instruments to mimic their assessment instruments may not take error-spotting exercises seriously.
  • Error-spotting exercises require considerably more effort to design. In particular, they are less accessible to autodidacts constructing their own exercises.