Final answer:
Participants in an experiment should be divided into control and experimental groups using random assignment to ensure fairness and the reliability of results.
Step-by-step explanation:
In an experiment, it is best to divide participants into the control or experimental group by using random assignment. This method ensures that all participants have an equal chance of being assigned to either group, thereby reducing potential biases and ensuring that any observed differences between the groups are likely due to the manipulation of the independent variable.
Random assignment is a critical component of sound experimental design because it minimizes systematic differences between groups that could skew the results. For instance, to test the benefits of tutoring, participants would be randomly assigned to either receive tutoring (the experimental group) or not (the control group), and their performances would be compared to determine the effect of the intervention.