Tammy M. Long

What We Say Is Not What We Do: Effective Evaluation of Faculty Professional Development Programs

Professional development (PD) workshops designed to help faculty move from teacher- to learner-centered science courses for undergraduates are typically evaluated with self-reported surveys that address facultys satisfaction with a workshop, what they learned, and what they applied in the classroom. Professional development outcomes are seldom evaluated through analysis of observed teaching practices. We analyzed videotapes of biology faculty teaching following PD to address three questions: (1) How learner centered was their teaching? (2) Did self-reported data about faculty teaching differ from the data from independent observers? (3) What variables predict teaching practices by faculty? Following PD, 89% of the respondents stated that they made changes in their courses that included active, learner-centered instruction. In contrast, observational data showed that participation in PD did not result in learner-centered teaching. The majority of faculty (75%) used lecture-based, teacher-centered pedagogy, showing a clear disconnect between facultys perceptions of their teaching and their actual practices.

Nitrogen resorption in senescing tree leaves in a warmer, CO2-enriched atmosephere

The prediction that litter quality, and hence litter decomposition rates, would be reduced when plants are grown in a CO2-enriched atmosphere has been based on the observation that foliar N concentrations usually are lower in elevated [CO2]. The implicit assumption is that the N concentration in leaf litter reflects the N concentration in green leaves. Here we evaluate that assumption by exploring whether the process of seasonal nutrient resorption is different in CO2-enriched plants. Nitrogen resorption was studied in two species of maple trees (Acer rubrum L. and A. saccharum Marsh.), which were planted in unfertilized soil and grown in open-top chambers with ambient or elevated [CO2] in combination with ambient or elevated temperature. In the second growing season, prior to autumn senescence, individual leaves were collected and analyzed for N and dry matter content. Other leaves at the same and an adjacent node were collected for analysis as they senesced and abscised. This data set was augmented with litter samples from the first growing season and with green leaves and leaf litter collected from white oak (Quercus alba L.) saplings grown in ambient and elevated [CO2] in open-top chambers. In chambers maintained at ambient temperature, CO2 enrichment reduced green leaf N concentrations by 25% in A. rubrum and 19% in A. saccharum. CO2 enrichment did not significantly reduce resorption efficiency so the N concentration also was reduced in litter. There were, however, few effects of [CO2] on N dynamics in these leaves; differences in N concentration usually were the result of increased dry matter content of leaves. The effects of elevated [CO2] on litter N are inherently more difficult to detect than differences in green leaves because factors that affect senescence and resorption increase variability. This is especially so when other environmental factors cause a disruption in the normal progress of resorption, such as in the first year when warming delayed senescence until leaves were killed by an early frost. The results of this experiment support the approach used in ecosystem models in which resorption efficiency is constant in ambient and elevated [CO2], but the results also indicate that other factors can alter resorption efficiency.

Soil microbial activity in a Liquidambar plantation unresponsive to CO2-driven increases in primary production

The indirect responses of soil microbiota to changes in plant physiology effected by elevated atmospheric carbon dioxide have the potential to alter nutrient availability and soil carbon storage. We measured fine root density, microbial biomass nitrogen, rates of nitrogen mineralization and nitrification, substrate utilization by soil bacteria and extracellular enzyme activities (EEA) associated with bulk soil and fine root rhizoplanes within a 3-year period at the Oak Ridge National Laboratory (ORNL) Free Air Carbon Enrichment (FACE) experiment, situated in a Liquidambar styraciflua plantation. Rhizoplane EEA was similar to that of bulk soil. Prior studies have reported a 21% increase in net primary production (NPP) in the enrichment plots and evidence that additional carbon is reaching the soil system, however we observed no response in any of the variables we measured. These results, which contrast with those from other temperate forest FACE sites, suggest that soil characteristics can influence the magnitude and timing of belowground responses.

Just the Facts? Introductory Undergraduate Biology Courses Focus on Low-Level Cognitive Skills

Introductory biology courses are widely criticized for overemphasizing details and rote memorization of facts. Data to support such claims, however, are surprisingly scarce. We sought to determine whether this claim was evidence-based. To do so we quantified the cognitive level of learning targeted by faculty in introductory-level biology courses. We used Blooms Taxonomy of Educational Objectives to assign cognitive learning levels to course goals as articulated on syllabi and individual items on high-stakes assessments (i.e., exams and quizzes). Our investigation revealed the following: 1) assessment items overwhelmingly targeted lower cognitive levels, 2) the cognitive level of articulated course goals was not predictive of the cognitive level of assessment items, and 3) there was no influence of course size or institution type on the cognitive levels of assessments. These results support the claim that introductory biology courses emphasize facts more than higher-order thinking.

Rapid assay for amidohydrolase (urease) activity in environmental samples

The use of microplate technology for enzyme assays has made it economical to measure a wide range of activities in environmental samples. Urease is one of the most widely measured soil enzyme activities, but current methods are cumbersome. We have developed a rapid, safe and sensitive assay that can be performed on microplates.

Microbial Community Responses to Atmospheric Carbon Dioxide Enrichment in a Warm-Temperate Forest

Forest productivity depends on nutrient supply, and sustained increases in forest productivity under elevated carbon dioxide (CO2) may ultimately depend on the response of microbial communities to changes in the quantity and chemistry of plant-derived substrates, We investigated microbial responses to elevated CO2 in a warm-temperate forest under free-air CO2 enrichment for 5 years (1997–2001). The experiment was conducted on three 30 m diameter plots under ambient CO2 and three plots under elevated CO2 (200 ppm above ambient). To understand how microbial processes changed under elevated CO2, we assayed the activity of nine extracellular enzymes responsible for the decomposition of labile and recalcitrant carbon (C) substrates and the release of nitrogen (N) and phosphorus (P) from soil organic matter. Enzyme activities were measured three times per year in a surface organic horizon and in the top 15 cm of mineral soil. Initially, we found significant increases in the decomposition of labile C substrates in the mineral soil horizon under elevated CO2; this overall pattern was present but much weaker in the O horizon. Beginning in the 4th year of this study, enzyme activities in the O horizon declined under elevated CO2, whereas they continued to be stimulated in the mineral soil horizon. By year 5, the degradation of recalcitrant C substrates in mineral soils was significantly higher under elevated CO2. Although there was little direct effect of elevated CO2 on the activity of N- and P-releasing enzymes, the activity of nutrient-releasing enzymes relative to those responsible for C metabolism suggest that nutrient limitation is increasingly regulating microbial activity in the O horizon. Our results show that the metabolism of microbial communities is significantly altered by the response of primary producers to elevated CO2. We hypothesize that ecosystem responses to elevated CO2 are shifting from primary production to decomposition as a result of increasing nutrient limitation.

Harnessing technology to improve formative assessment of student conceptions in STEM: Forging a national network

Concept inventories, consisting of multiple-choice questions designed around common student misconceptions, are designed to reveal student thinking. However, students often have complex, heterogeneous ideas about scientific concepts. Constructed-response assessments, in which students must create their own answer, may better reveal students’ thinking, but are time- and resource-intensive to evaluate. This report describes the initial meeting of a National Science Foundation–funded cross-institutional collaboration of interdisciplinary science, technology, engineering, and mathematics (STEM) education researchers interested in exploring the use of automated text analysis to evaluate constructed-response assessments. Participants at the meeting shared existing work on lexical analysis and concept inventories, participated in technology demonstrations and workshops, and discussed research goals. We are seeking interested collaborators to join our research community.

Using Avida-ED for Teaching and Learning About Evolution in Undergraduate Introductory Biology Courses

Evolution is a complex subject that requires knowledge of basic biological concepts and the ability to connect them across multiple scales of time, space, and biological organization. Avida-ED is a digital evolution educational software environment designed for teaching and learning about evolution and the nature of science in undergraduate biology courses. This study describes our backward design approach to developing an instructional activity using Avida-ED for teaching and learning about evolution in a large-enrollment introductory biology course. Using multiple assessment instruments, we measured student knowledge and understanding of key principles of natural selection before and after instruction on evolution (including the Avida-ED activity). Assessment analysis revealed significant post-instruction learning gains, although certain evolutionary principles (most notably those including genetics concepts, such as the genetic origin of variation) remained particularly difficult for students, even after instruction. Students, however, demonstrated a good grasp of the genetic component of the evolutionary process in the context of a problem on Avida-ED. We propose that: (a) deep understanding of evolution requires complex systems thinking skills, such as connecting concepts across multiple levels of biological organization, and (b) well designed use of Avida-ED holds the potential to help learners build a meaningful and transferable understanding of the evolutionary process.

Introductory Biology Students’ Conceptual Models and Explanations of the Origin of Variation

Introductory biology students struggle to incorporate the molecular genetic origin of variation in their evolutionary reasoning framework. Meaningful learning of this concept may require 1) multiple cycles of instruction, assessment, and feedback; and 2) assessment forms, such as conceptual models, that promote and reveal mechanistic and causal reasoning.

Teaching Assistant Professional Development in Biology: Designed for and Driven by Multidimensional Data

Graduate teaching assistants (TAs) may receive professional development (PD) to enhance their teaching of undergraduates. However, data about the effectiveness of these PD programs are almost entirely self-reported. Using an evaluation framework, we found that TA multidimensional data were more informative for evaluating the efficacy of TA PD.