(Cheng & Gilbert, 2015). Diagram comprehension has been described
as “a key competence for students in mastering many of the biological
theories” (Kragten et al., 2013, p. 1786).
Food webs are typical of science diagrams because they require
strategies, knowledge, and skills specific to the biology science
domain (Lowe, 2000; Cheng et al., 2001). We can expect that
school students inexperienced in reading science diagrams will
view them differently from their teachers. Questions about students’ interpretive approaches to food web diagrams bear thinking
about. Do students pay more attention to different parts of food
webs? Do they mentally represent food webs at a number of levels?
Do they mentally separate food webs into smaller components,
enabling conceptual chunking to accommodate the complex concepts involved? A problematic aspect of science diagrams for inexperienced learners is the use of graphical conventions that differ
depending on diagram type and science domain. Especially confusing is the use of arrows, because they can convey a variety of meanings in science diagrams, some simultaneously (Heiser & Tversky,
2006). Arrows are a common convention in biology diagrams
(Cheng & Gilbert, 2015).
An earlier, but pertinent study investigated how the presence of
arrows influenced secondary students’ interpretation of science diagrams (Schollum, 1983). Students were shown paired diagrams,
with and without arrows, and asked to explain what each meant to
them. Some pupils gave different meanings to arrows than those
intended to be conveyed. For example, students could explain
clearly what food chain diagrams showed without arrows, providing
responses such as “the bugs eat the bush, the birds eat the bugs.” The
diagrams including arrows resulted in a wider range of views that
were expressed less confidently. Half the students were puzzled, as
indicated by replies such as “This looks like the cabbage is going
to eat the caterpillar” and “Those arrows are around the wrong
way” (ibid., p. 47).
In a larger study involving elementary and high school stu-
dents, 5- to 16-year-olds were shown a food web diagram to probe
the reasoning they used to think about populations of organisms
(Leach et al., 1995). Although the aim was not to find out whether
students could interpret the diagrams, some of the findings are rel-
evant to the current study. Five- to 11-year-olds tended to “talk
about organisms in the singular, suggesting a relationship between
one predator and prey organism as opposed to relationships
between populations” (Leach et al., 1996, p. 136). Students also
had difficulty interpreting food chains in which the energy
exchange relationship is depicted by arrows. The authors noted
that use of food web models by students differed from their
intended use: students applied linear causal reasoning and tended
to frame their explanations in terms of individual organisms rather
than populations (ibid., p. 140). In another study grade 6–8 stu-
dents reportedly had difficulty reading food webs when symbols
(e.g., A and B) were used instead of names of familiar organisms.
Students interpreted arrows as pointing from predator to prey, sug-
gesting unfamiliarity with the conventional meaning of arrows in
food webs (Lennon & DeBoer, 2008). Food webs are difficult to
understand fully at the elementary level due to the biological con-
ceptions of the complex ecological systems involved. Such meaning
is not embedded in the diagram, but must be actively created in the
mind of the reader (Cheng & Gilbert, 2015, p. 144). The current
study explores elementary level students’ interpretation of food
Overview of Research Methods
The present study conducted in Australia adopted a qualitative
approach (Johnson & Christensen, 2004; Maxwell, 2005). Participants
were Year 3 (8–9 years old, n = 10) and Year 5 (10–11 years, n = 11)
students from a suburban, government school. Males and females were
selected by their class teachers to include low-, medium-, and high-ability students. Individual students were involved in semi-structured,
task-based interviews. Separate teacher interviews and examination of
students’ notebooks confirmed that science was given low priority in
the school. Students were not formally taught about food webs prior
to or during the study.
The data were collected in three steps. First, each participant was
shown the toy objects in Figure 1 and asked if they could answer the
question, “What eats what out of these things?” This was designed to
elicit prior knowledge and help students feel at ease in expressing
their ideas by having tangible objects to focus on.
Second, a typical, simple food web diagram intended for assessment of Year 4 primary students was used. The visual-only food
web diagram (modified to remove labels) in Figure 2 was shown,
and the student was encouraged to talk freely (out loud) about
the image to tell the researcher (author), “What do you think this
picture is telling you?” The “think aloud” method allowed me to
understand what the student was thinking as they interacted with
the diagram. This visual-only version also tested whether text was
essential to diagram reading.
Third, if students struggled to make sense of the diagram, they
were shown the labelled food web in Figure 3. This version included
text naming the organisms and was modified to include arrow meaning based on another question from the same source. This modification
was made because “the function of an arrow in a process diagram is
usually conveyed by a label” (Kragten et al., 2013, p. 1788). This version tested whether this information helped or hindered the students.
The entire interview was repeated after one month to test for long-term
learning effects. No direct instruction about food webs had occurred
during this time period.
Figure 1. Bird, snail, frog, and artificial plant.