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In my last post, we looked at a very complicated graph (pictured below) taken from a science section in The Real ACT Prep Guide, Third Edition. Then we saw that even the most complex infographics can be deciphered in the same way as the simpler, more common ACT Science graph types. Any Science graph can be decoded by using the three graph comprehension strategies from the Magoosh High School Blog.

In Parts 1 and 2, we went through two of these three key strategies: recognizing the parts of the graph and connecting the graph to the reading passage.

Just by looking at the graph, we can clearly see all of the variables on the x-axis (horizontal) and the y-axis (vertical). From left to right along x, we see regions for atmospheric conditions (density, pressure, and average temperature) and a band of four different categories of incoming solar radiation. And from top to bottom along y, we see markers for altitude and layered labels that read thermosphere, mesopause, mesosphere, stratopause, stratosphere, tropopause, troposphere, and surface.

And once you apply strategy two and read the passage (inset below), the full meaning of the graph comes into focus: the graph labels different layers of the atmosphere, indicates the layers’ ranges of altitude, shows how atmospheric density and pressure steadily changes with each different layer, shows average temperature fluctuation across the layers, and indicates the way that different types of solar radiation either penetrate atmospheric layers or are absorbed by the layers.

Passage:

• Certain layers of the Earth’s atmosphere absorb particular wavelengths of solar radiation while letting others pass through. Types of solar radiation include X-rays, ultraviolet light, visible light, and infrared radiation. The cross section Earth’s atmosphere below illustrates the altitudes at which certain wavelengths are absorbed. The arrows point to the altitudes at which solar radiation or different ranges of wavelengths are absorbed. The figure also indicates the layers of the atmosphere and how atmospheric density, pressure, and temperature vary with altitude.

Between the passage that describes the graph and the various elements on the graph itself, you get a reasonably complete idea of what the graph means. However, sometimes it can be hard to fully understand every way a graph can be used, and every kind of information that can be extrapolated from a graph. This can be true even for the simpler, more common types of ACT Science graphs. This is absolutely true for a complicated graph like the one above.

This is where the third strategy for understanding ACT Science graphs comes in by using the actual test questions to gain a complete, sufficient understanding of the infographic. ACT Science questions can sometimes provide new information about a graph, and the question set as a whole acts as a guide to help you correctly and interpret informational images.

There are five questions for this particular graph and passage (found on page 195 of The Real ACT Prep Guide). The first question asks you to identify the upper boundary of one of the atmospheric layers, and indicates that this upper boundary has name marked ending in ‘sphere’. This makes it much more obvious that the labels ending in ‘pause’ represent the boundaries of atmospheric layers, an important distinction that test-takers might not catch by just looking at the graph and reading the passage.

Another question asks about how air temperature is influenced by solar radiation at different atmospheric levels. This helps test-takers understand that radiation influences the uneven temperature flux across atmospheric layers, as marked by the “zig-zag” arrow within the average atmospheric temperature region of the graph.

These are just two examples, in this ACT Science subsection, all five questions provide further insight into some aspect of the graph. As I said, this third strategy is vital to understanding the most complex infographics you’ll see in ACT Science.

## The Takeaway

In these last three posts, I looked in great detail at the three strategies for understanding ACT Science graphs, which include, recognizing the parts of the graph, connecting the reading to the graph and using the questions to learn even more about the graph. These three approaches will work on any graph in ACT Science. Once you get the hang of these ACT Science skills for interpreting visuals, you’ll be able to understand both simple and complex graphs on the ACT with similar ease.