Abstract. Boundary‐layer resistances of aquatic bryophytes for CO2 diffusion in water were estimated from wind tunnel measurements of evaporation of aniline in air, using the principle of dynamic similarity. The results indicated resistances at water velocities between 0.02 and 0.2 m s −1 ranging from about 35 to 5 s mm−1 and 70 to 9 s mm−1, respectively, for the mat‐forming liverworts Nardia compressa and Scapania undulata, measured on a projected area (canopy) basis. Over a range of velocities from 0.01 to 0.2 m s−1 the estimated CO2 boundary‐layer resistance of the streamer‐like shoots of the moss Fontinalis antipyretica is between about 180 and 15 s mm−1. Comparison with experiments on photosynthetic 14CO2‐uptake at a range of water velocities suggests that boundary‐layer resistance limits photosynthesis at velocities below about 0.01 m s−l in Fontinalis and below about 0.1 m s−1 in the mat‐forming species. It is suggested that high leaf‐area index allows the mat growth form more effectively to exploit the low boundary‐layer resistance at high velocities while remaining relatively invulnerable to drag. By contrast, the streamer form allows Fontinalis to maximize surface area under conditions where boundary‐layer resistance is limiting.

This paper describes a design for an immediate immersion of computational thinking into current high school math classrooms in Alabama. Most schools in our region have eliminated computer science classes from the curriculum. Alabama has an existing state initiative to improve mathematics, science and technology education in K-12. The Alabama Math, Science, and Technology Initiative (AMSTI) emphasizes learning by doing, with hands-on, activity based instruction. We have developed an instructional treatment that uses strategically designed computer exercises to push students to form the mental foundation necessary for abstraction and generalization. We selected popular problems from the AMSTI mathematics curriculum and applied our instructional design.The first step we took in implementing our plan for reintroducing computational thinking into the secondary schools was to conduct a workshop for math education leaders. This training was sponsored and supported by AMSTI. Results from the workshop included demonstrating to a select group of math education leaders that computer programming could be easily integrated with the AMSTI math curriculum and could be used to meet the educational goals of the initiative and the educators.

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