Different visual aids are useful for different types of relationships. A line graph is a great way to show trends and changes over time. A pie chart is great for showing parts of a whole, like how a budget is divided up. A bar graph is good for comparing different values side-by-side, like test scores in different classes. And a map is perfect for showing the location of something, like the distribution of a population. So it really depends on the relationship you want to show.