Visual aids often bring a new level of multimodality to a piece of written work. Multimodality refers to the idea that sharing information encompasses more than just text. Often, there are multiple modes in a single communication, such as the written text, the spoken script, visualization with images, and so on. When a visual aid is available as part of a communication, it complements the writing, allowing readers to dive deeper into the material.

As you read, you will often come across charts, graphs, and infographics. These are common visual aids. Audio, video, and slide presentations can be present as visual aids, too, especially in the digital sphere.

It is just as important to read the visual aids as it is to read the written text. So, as you read the material, be sure that you focus on both the written text and the visual aids. Don’t just read the text, and avoid just looking at the visual aids. Instead, pay equal attention to both to see how they complement each other.

Specific kinds of charts and graphs accomplish different things. This is important to keep in mind as you evaluate data and data sources. For instance:

Scatter plots show the distribution of data points.

A scatter plot of age and final exam score variables. Notice this scatter plot does not indicate a linear relationship. The points do not appear to follow a trend. In other words, there does not appear to be a relationship between the age of the student and the score on the final exam.

A scatter plot of cricket chirps vs. temperature. This data does indicate a linear relationship (shown here by the red line), which means that we may be able to guess at chirps-temperature relationships beyond the recorded data we have (a process known as interpolation or extrapolation).

Line charts are usually used to show trends, for instance comparing data over time or distance.

U.S. Unemployment Rate, 1975–2014.

Altitude–Air-Density Relationship. The thin air at high altitudes explains why many mountain climbers need to use oxygen tanks as they reach the top of a mountain.

Bar graphs usually compare quantities of different things. So while you might measure the changing population of one country with a line graph, you would compare the populations of different countries with a bar graph:

The graph shows the 12 countries of the world with the largest populations. The height of the bars in the bar graph shows the size of the population for each country.

Pie charts show proportions of a whole. A circle represents a group as a whole. The slices of this circular “pie” show the relative sizes of subgroups.

Pie Graphs of the U.S. Age Distribution (numbers in millions).

5 Step Approach for Reading Charts and Graphs

Visual data are meant to be “read,” just like text on a page. Images with data often contain crucial information that isn’t available elsewhere in a text.

Ask these questions when you encounter visual data in your reading:

1. What is the topic?
   • Look for the title and reword it in your own words
2. What is being measured?
   • Look for labels to get an idea of what the graph is saying
3. How is it being measured?
   • Look for units
   • Ask yourself if the units make sense with what you know about the graph so far
4. Is color-coding used and if so, how?
   • Color-coding is often used to add additional information to a graph without taking up extra space
   • Check for a key that explains the color coding
5. Can I summarize this information in my own words?
   • Look for a trend or a piece of information that you find interesting and mentally form a sentence about it
   • If you are struggling with this step, don’t get frustrated or give up. Instead, start over from Step 1. Each time you investigate the visual data you are building up your knowledge and understanding of the information.