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- Creators: Anbar, Ariel
- Creators: Atkinson, Robert K
Description
This dissertation is presented in two sections. First, I explore two methods of using stable isotope analysis to trace environmental and biogeochemical processes. Second, I present two related studies investigating student understanding of the biogeochemical concepts that underlie part one. Fe and Hg are each biogeochemically important elements in their own way. Fe is a critical nutrient for phytoplankton, while Hg is detrimental to nearly all forms of life. Fe is often a limiting factor in marine phytoplankton growth. The largest source, by mass, of Fe to the open ocean is windblown mineral dust, but other more soluble sources are more bioavailable. To look for evidence of these non-soil dust sources of Fe to the open ocean, I measured the isotopic composition of aerosol samples collected on Bermuda. I found clear evidence in the fine size fraction of a non-soil dust Fe source, which I conclude is most likely from biomass burning. Widespread adoption of compact fluorescent lamps (CFL) has increased their importance as a source of environmental Hg. Isotope analysis would be a useful tool in quantifying this impact if the isotopic composition of Hg from CFL were known. My measurements show that CFL-Hg is isotopically fractionated, in a unique pattern, during normal operation. This fractionation is large and has a distinctive, mass-independent signature, such that CFL Hg can be uniquely identified from other sources. Misconceptions research in geology has been a very active area of research, but student thinking regarding the related field of biogeochemistry has not yet been studied in detail. From interviews with 40 undergraduates, I identified over 150 specific misconceptions. I also designed a multiple-choice survey (concept inventory) to measure understanding of these same biogeochemistry concepts. I present statistical evidence, based on the Rasch model, for the reliability and validity of this instrument. This instrument will allow teachers and researchers to easily quantify learning outcomes in biogeochemistry and will complement existing concept inventories in geology, chemistry, and biology.
ContributorsMead, Chris (Author) / Anbar, Ariel (Thesis advisor) / Semken, Steven (Committee member) / Shock, Everett (Committee member) / Herckes, Pierre (Committee member) / Hartnett, Hilairy (Committee member) / Arizona State University (Publisher)
Created2014
Description
Evidence suggests that Augmented Reality (AR) may be a powerful tool for
alleviating certain, lightly held scientific misconceptions. However, many
misconceptions surrounding the theory of evolution are deeply held and resistant to
change. This study examines whether AR can serve as an effective tool for alleviating
these misconceptions by comparing the change in the number of misconceptions
expressed by users of a tablet-based version of a well-established classroom simulation to
the change in the number of misconceptions expressed by users of AR versions of the
simulation.
The use of realistic representations of objects is common for many AR
developers. However, this contradicts well-tested practices of multimedia design that
argue against the addition of unnecessary elements. This study also compared the use of
representational visualizations in AR, in this case, models of ladybug beetles, to symbolic
representations, in this case, colored circles.
To address both research questions, a one-factor, between-subjects experiment
was conducted with 189 participants randomly assigned to one of three conditions: non
AR, symbolic AR, and representational AR. Measures of change in the number and types
of misconceptions expressed, motivation, and time on task were examined using a pair of
planned orthogonal contrasts designed to test the study’s two research questions.
Participants in the AR-based condition showed a significantly smaller change in
the number of total misconceptions expressed after the treatment as well as in the number
of misconceptions related to intentionality; none of the other misconceptions examined
showed a significant difference. No significant differences were found in the total
number of misconceptions expressed between participants in the representative and
symbolic AR-based conditions, or on motivation. Contrary to the expectation that the
simulation would alleviate misconceptions, the average change in the number of
misconceptions expressed by participants increased. This is theorized to be due to the
juxtaposition of virtual and real-world entities resulting in a reduction in assumed
intentionality.
alleviating certain, lightly held scientific misconceptions. However, many
misconceptions surrounding the theory of evolution are deeply held and resistant to
change. This study examines whether AR can serve as an effective tool for alleviating
these misconceptions by comparing the change in the number of misconceptions
expressed by users of a tablet-based version of a well-established classroom simulation to
the change in the number of misconceptions expressed by users of AR versions of the
simulation.
The use of realistic representations of objects is common for many AR
developers. However, this contradicts well-tested practices of multimedia design that
argue against the addition of unnecessary elements. This study also compared the use of
representational visualizations in AR, in this case, models of ladybug beetles, to symbolic
representations, in this case, colored circles.
To address both research questions, a one-factor, between-subjects experiment
was conducted with 189 participants randomly assigned to one of three conditions: non
AR, symbolic AR, and representational AR. Measures of change in the number and types
of misconceptions expressed, motivation, and time on task were examined using a pair of
planned orthogonal contrasts designed to test the study’s two research questions.
Participants in the AR-based condition showed a significantly smaller change in
the number of total misconceptions expressed after the treatment as well as in the number
of misconceptions related to intentionality; none of the other misconceptions examined
showed a significant difference. No significant differences were found in the total
number of misconceptions expressed between participants in the representative and
symbolic AR-based conditions, or on motivation. Contrary to the expectation that the
simulation would alleviate misconceptions, the average change in the number of
misconceptions expressed by participants increased. This is theorized to be due to the
juxtaposition of virtual and real-world entities resulting in a reduction in assumed
intentionality.
ContributorsHenry, Matthew McClellan (Author) / Atkinson, Robert K (Thesis advisor) / Johnson-Glenberg, Mina C (Committee member) / Nelson, Brian C (Committee member) / Arizona State University (Publisher)
Created2019