This Science video introduces teachers to a fair test investigation exploring how toothbrush bristle hardness affects cleaning effectiveness. It guides pupils in identifying variables, planning the test, and making a prediction based on prior knowledge. The method involves using model teeth, timing cleaning attempts, and recording results to compare the performance of soft, medium, and hard brushes. The activity also provides opportunities to discuss the reliability of results, the limitations of the model, and how findings may differ in real-life contexts.

This video is part of Kapow Primary’s Science – investigation. It supports teachers in developing pupils’ understanding of fair testing, evaluation, and scientific justification. The lesson encourages children to suggest alternative methods, extend the investigation, and consider why real-world recommendations – such as dentists favouring soft brushes – may differ from experimental results, helping to build their ability to question and justify conclusions using scientific reasoning.

Science, key stage 2, Year 4, Animals including humans: Digestion and food, Lesson 3: Investigating dental hygiene