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      Lesson details

      Learning outcome

      I can make changes to how my model is trained to improve the accuracy of the output.

      Key learning points

      1. Data cleaning can remove outliers so the model "learns" real patterns instead of noise.
      2. False positives occur when data is misclassified.
      3. Creating a null class reduces the chances of misclassification.

      Keywords

      • Misclassification - when a model predicts the wrong class for a sample

      • Data cleaning - the process of detecting and correcting, or removing, corrupt or inaccurate data from a data set

      • Noise - unwanted or random variations in data that don’t represent meaningful patterns

      • False positive - a sample that has been incorrectly classified

      Common misconception

      More data is always better as it means the model can be better informed to make a prediction.

      Poorly labelled or inconsistent data can make a model's predictions inaccurate. It is better to use a smaller amount of higher quality data to make more accurate predictions.

      Teacher tip

      A null class is a concept that learners may find difficult. Model the importance of recording a null class when training a model.

      Equipment

      Pupils will need access to a physical device to capture data and a means of creating a data-driven application. Examples in this lesson use micro:bits and CreateAI https://oak.link/createai

      File needed for this lesson

      microbit-Oak 1.29 MB (HEX)

      Download this file to use in the lesson.

      Licence

      This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0
      except where otherwise stated. See Oak's terms & conditions
      (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

      6 Questions

      Q1.
      A machine learning model can make incorrect predictions if the training data has .

      Correct Answer: bias, Bias

      Q2.
      A model’s score tells us how likely the model’s prediction is correct.

      Correct answer: confidence
      accuracy
      certainty

      Q3.
      Match the problem with its potential cause in machine learning.

      Correct Answer:incorrect predictions,poor-quality training data
      Correct Answer:unexpected results,presence of outliers
      Correct Answer:model favours certain outcomes,bias in the data set
      Correct Answer:low confidence score,data does not fit the trained model

      Q4.
      A classifier learns by analysing between samples and grouping them into classes.

      Correct Answer: patterns

      Q5.
      What is one way to improve a machine learning model’s accuracy?

      decreasing the amount of training data
      increasing the amount of training data
      Correct answer: adding more diverse and well-labelled training data
      removing all boundaries between classes

      Q6.
      Which of the following best describes an outlier in a data set?

      a missing value that has no impact on model performance
      Correct answer: a data point that does not follow the general pattern of the rest of the data
      a data point that is identical to all others

      6 Questions

      Q1.
      What is the main benefit of training an AI model on diverse data?

      it makes the model more complex
      it helps the model learn faster
      Correct answer: it reduces bias in the model's predictions
      it makes the model easier to build

      Q2.
      Cleaning data enhances the of a machine learning model.

      Correct Answer: accuracy, ccuracy

      Q3.
      Match the following terms with their descriptions.

      Correct Answer:data cleaning,removing irrelevant data
      Correct Answer:noise,unwanted variations in data
      Correct Answer:misclassification,when a model predicts the wrong class

      Q4.
      What is an outlier in data?

      a very important data point
      a data point that is similar to others
      Correct answer: a data point that is significantly different from others
      a data point that is always correct

      Q5.
      Adding a null class helps prevent in machine learning models

      Correct Answer: misclassification, isclassification

      Q6.
      Why is it important to include data from people with different movement styles when training a model to classify movements?

      it makes the model look more impressive
      it makes the model run faster
      it makes the model smaller
      Correct answer: it ensures the model can recognise valid movements from diverse individuals

      To help you plan your 9 computing lesson on: Improving a model, download all teaching resources for free and adapt to suit your pupils' needs...