In this deck, we'll explore the AQA required practical for investigating human reaction time. Reaction time is the time it takes for you to respond to a stimulus. We'll cover the aim of the investigation, the variables you need to control, a common method called the ruler drop test, and how to make your results accurate and valid.

In any scientific investigation, we need to understand our variables. The independent variable is the one you change on purpose to see what effect it has. For example, you could investigate the effect of caffeine, so the independent variable would be whether the person has had a caffeinated drink or not. The dependent variable is the one you measure – in this case, it's the person's reaction time. Finally, control variables are all the things you must keep the same to ensure a fair test, such as using the same person, the same hand, and ensuring there are no distractions.