Three of the most common ways to investigate hypotheses are controlled experiments, observational experiments and modelling.
Controlled Experiments
A controlled experiment is a test that involves changing one factor in order to see how it affects some other factors. Experiments also involve controlling and keeping constant as many factors as possible.
Variables
Variables are factors in an experiment that can change and have different values. In a controlled experiment it is important to only change one variable at a time and to observe or measure the effect of this change.
Observational Experiments
There are many aspects of the natural world we cannot control. However, we can still form hypotheses about these types of things. We can also test our hypotheses with scientific investigation. One of the ways we can do this is with observational experiments.
Observational experiments are useful when it is difficult to control or change the cause variable. They are also useful when it is difficult to keep other factors constant which means that they cannot be ruled out as having a possible effect.
Modelling
Models provide a way to understand things in the world around us. Models are used to carry out experiments that cannot be carried out in the real world, such as experiments to predict the weather. Some models are made in classrooms and laboratories while others are made on computers.