student interviews, we also found differences in the types of ideas held
by students experiencing the two versions of the curriculum. Students’ ideas in year 1 tended to focus primarily on the characterization
of observable plant structures and traits, but their ideas tended to be
piecemeal and lacked substantial connections to explain how plant
structures and functions can support ideas about inheritance. By contrast, students in year 2 started to make more connections between
plant inheritance and the stage of reproduction within life cycles.
Students also tended to use their specific knowledge about plant
structures (e.g., the seed) and processes (e.g., reproduction) to make
explanations about mechanisms of inheritance.
Prior research has shown that heredity-related concepts are challenging topics for students of all ages (e.g., Ronald, 2011; Elmesky,
2013; Anderson et al., 2014), including early learners in grades
K–5. However, these concepts are central outcomes for science
learning (Duncan et al., 2009; NGSS Lead States, 2013). The results
we present here contribute to the research body on elementary students’ reasoning about heredity (e.g., Venville & Donovan, 2008;
Cisterna et al., 2013) and model-based instruction in elementary
science learning environments (Acher et al., 2007; Schwarz et al.,
2009; Manz, 2012; Zangori & Forbes, 2014, 2015; Forbes et al.,
2015; Louca & Zacharia, 2015; Zangori et al., 2017).
First, our findings show that students experiencing the year 2
(model-based) version of the curriculum held more sophisticated
ideas about two of three target concepts (trait inheritance and trait
variation) than did students in year 1. For elementary students, it is
critical that curriculum design support students in addressing these
concepts about heredity because they will form a foundation for
learning in subsequent grades. The use of model-based curricula
has the potential to help elementary students better organize their
ideas about heredity (Venville & Donovan, 2008; Puig et al.,
2017) and represent the complexity of science phenomena (
Zangori & Forbes, 2014, 2015; Forbes et al., 2015; Zangori et al.,
2017). Our results reinforce this perspective, and we argue that
the inclusion of model-based tasks can help students organize
and represent their ideas about trait inheritance and trait variation
(Rotbain et al., 2006; Venville & Donovan, 2008).
Second, our findings illustrate ways in which students’ ideas
Limitations & Conclusions
were more robust in year 2. Prior research suggests that students
tend to struggle with making explanations about heredity-related
concepts (e.g., Venville et al., 2005; Duncan & Reiser, 2007), spe-
cifically plant structure and function (Zangori & Forbes, 2015;
Wynn et al., 2017). Evidence shows that students experiencing
the model-based version of the curriculum made stronger connec-
tions between corn structures and processes and used their knowl-
edge to explain how traits were passed from parent plants to
offspring. Students were also able to recognize the role of the spe-
cific structures involved in plant reproduction (Lewis & Wood-
Robinson, 2000; Tytler et al., 2004) and better understand that
plants are living organisms (Barman et al., 2006; Zangori & Forbes,
2014). We tentatively posit that the model-based curriculum
allowed students to sequence and organize their ideas (Krajcik &
Merritt, 2012), make key processes and mechanisms about inheritance
explicit (Duncan & Reiser, 2007; Ronald, 2011; Elmesky, 2013), and
develop heredity-specific vocabulary (Venville & Donovan, 2008).
Our results suggest that organizing a heredity-based curriculum
around scientific modeling may support students’ learning about
target concepts such as trait inheritance and trait variation.
We recognize the limitations of the present study. First, our comparative analysis of curriculum iterations is based on similar curricular tasks and student interviews. The student tasks, in particular,
may not represent the complete variety of ideas about the three
target concepts. Rather, these tasks were selected because they
remained as comparable “checkpoints” in the two versions of the
curriculum. Second, we did not include pre/post measures for these
three target concepts that would have allowed us to more directly
assess the impact of both curriculum iterations. Since students were
not randomly assigned to the curriculum iterations, it is possible
that observed differences do not account for preexisting differences
in the populations of students. Future studies could replicate this
research with a larger sample size of randomly assigned students
and classrooms. Despite these limitations, and given the importance of developing students’ heredity-related ideas from the earliest ages, this study provides in-depth evidence about elementary
students’ ideas about heredity-related concepts and contributes to
efforts to support effective teaching and learning in the life sciences.
This work is supported by grant no. 2016-31100-06031 (project no.
1006539) from the USDA National Institute of Food and Agriculture. We thank the teachers and students who made this research
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