What special challenges do science texts typically pose for students?
Science texts often pose a number of challenges to the uninitiated. There can be difficult new
words, or familiar words with unfamiliar meanings. Abstract nouns swallow up complex
processes, and passive verbs conceal the doers of deeds. Text sits cheek by jowl with other
modes of representation in ways that are supposed to clarify information, but that may require
new interpretive skills. Below are brief discussions of some of these challenges.
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Academic and Scientific Language.
Science texts use lots of unfamiliar terms. While these terms support clear, precise
communication for the initiated, they are like a foreign language for students. Students need help
learning to interpret scientific vocabulary through the use of visual representations, identification
of common prefixes and suffixes, or discussion of the different meanings words can have in
different contexts.
Logical Connectives.
Logical connectives, such as coordinating and subordinating conjunctions, help to clarify
relationships.
Jack left and Jill arrived.
Jack left because Jill arrived.
Jack left even though Jill arrived.
Students need to learn the meaning of the logical connectives they encounter, but science
textbooks for children often present an opposite problem: missing logical connectives. In an
effort to improve accessibility for struggling readers, textbook editors may remove logical
connectives, breaking complex sentences to simple, independent clauses. This kind of
simplification can be a double-edged sword, though, according to linguistic research. When you
change
The earth goes through different seasons because it tilts on its axis.
to
The earth goes through different seasons. It tilts on its axis.
You get rid of a complex sentence; but you also get rid of the main point: the because, the causal
relationship between the two clauses. Science teachers may need to help their students spot the
underemphasized relationships in science texts.
Polysemy.
Many words have multiple meanings. While terms like power, organic, and theory might have
relatively fixed meanings when used in scientific discourse, these same well-traveled words bring
baggage from many other contexts. Students need to learn the science-specific definitions of
such words, and they also need to learn how to interpret polysemous words appropriately
according to context. For example, only the third sentence below uses the word organic in its
narrow scientific sense:
Most of the scenes were organic to the plot of the movie, but the director left in a few that
seemed gratuitous.
When she took up organic farming, she stopped using synthetic pesticides and fertilizers and
turned her chickens loose to prey on the pests and manure the crops.
Many organic compounds, such as hydrogen cyanide (HCN), are extremely toxic.
Nominalization.
For the sake of efficiency, specialists in science and other fields often pack descriptions of
complex processes into single nouns, a process called nominalization. The word nominalization is
itself an example of nominalization, standing in, as it does, for a complex linguistic practice.
Geologists can just toss off the term stratification instead of going into lengthy descriptions of
wind and water depositing layers (strata) of different material over time. Chemists use words
like evaporation, condensation, sublimation, and deposition instead of getting bogged down in
elaborate descriptions every time they need to mention a phase change.
Nominalizations become transparent and helpful to the initiated, increasing the density of
information. But they can present an opaque barrier to students. Nominalization conceals agency
—who is doing what?—and converts concrete events into abstractions. Students need their
teachers to help them unpack the meaning of nominalizations.
Lexical Density.
The ratio of content words (nouns, adjectives, verbs, and adverbs) to function words (pronouns,
prepositions, auxiliary verbs, determiners, exclamations, and conjunctions) is called lexical density.
More content words mean greater density. Compared to typical narrative texts that students
read, science texts tend to have high lexical density, with lots of challenging vocabulary that
defies skimming. Students need to learn what the words mean, but even if they know the
vocabulary they must learn to read dense text relatively slowly, breaking, annotating, reflecting,
and rereading.
Multimodality.
The content of science is a heavy burden for words alone to bear, and so science texts resort to
other of modes of communication as well. Chemical symbols represent the elements,
illustrations range from the relatively concrete to the abstract and schematic, graphs and charts
represent a multitude of patterns, and mathematical notations capture systematic relationships.
Molecules can be represented in space-filling models to emphasize their overall shape, ball-andstick models to emphasize the geometry of their bonds, or structural formulas that are a hybrid
of text and schematic illustration. The various representations in a science text can reinforce
each other, illuminate different aspects of a phenomenon or idea, and meet the needs of students
with various learning styles; but the multimodality of these texts can also be challenging. Students
must strive to integrate and interpret multiple channels of a semiotic symphony.
Passive Voice.
Scientific texts such as reports, explanation, and experimental write-ups commonly employ the
passive voice to bolster a sense of objectivity.
Ideally, the results of an experiment should not depend on who performs it; data observed in
nature should be a property of nature, not of the observer. Scientists often use the passive voice
(“the precipitate was filtered,” “radiation was detected,” “fossilized remains were found below
this strata”) to minimize the sense of human agency in the phenomena they report. This absence
of agency is the opposite of what students are used to from reading, say, fiction ("Larry the lab
tech heaved a sigh and, for the hundredth time, filtered the precipitate").
One can debate whether the passive voice is overused in science writing (and lots of other
writing). But it is probably appropriate a lot of the time (tell us about the precipitation reaction,
not about Larry!), and in any case students need to get comfortable reading it.
Visualizations.
Scientific communication increasingly relies on visualizations, whether still, animated, or
interactive. The saying goes that a picture is worth a thousand words, and illustration can
certainly be an effective tool of science education. However, visual representations can also baffle
or mislead students. Teachers can help by providing explicit instruction on how to interpret
visual representations.
For example, where do students get the incorrect idea that the cycle of the seasons is caused by
variation in the earth’s distance from the sun throughout the year? One contributing culprit may
be the frequent schematic illustration of the earth’s orbit around the sun viewed in perspective,
from slightly above the earth’s plane of orbit. This perspective shows the earth’s orbit as an
ellipse with the sun at the center. Students may not understand the perspective in such images,
and may think that the exaggerated ellipse shows a “top” view (from solar north or south) of the
earth’s orbit.
It’s not that this way of illustrating the orbit of planets is bad. It can actually make it easier to
show how the tilt of the earth’s axis causes seasonal variation in sunlight in the earth’s northern
and southern hemispheres. The point is simply that pictures are not always as self-explanatory as
we may think they are. A picture may be worth a thousand words, but it may still call for
additional discussion.