Introduction to the Special Issue

The development of conceptions of evolution is a problem of both great practical concern and important theoretical interest. Many Americans do not understand basic principles of evolution, such as natural selection, and part of the reason may be that these concepts are notoriously difficult to learn and to teach. The four contributions in this special issue all investigate the development of conceptions in evolution. Several of the articles focus on the interaction between children’s prior beliefs and their interpretation and cognitive construction of evolutionary concepts. For example, essentialist beliefs (e.g., Gelman, 2003) may affect how children understand and interpret natural selection and the evolution of species. The four articles all demonstrate that prior beliefs constrain and influence how children and adults interpret what they observe and are taught about evolution. Taken together, the articles demonstrate the importance of taking a developmental approach to understanding the development of conceptions of evolution

Children’s Learning from Touch Screens: A Dual Representation Perspective

Parents and educators often expect that children will learn from touch screen devices, such as during joint e-book reading. Therefore an essential question is whether young children understand that the touch screen can be a symbolic medium – that entities represented on the touch screen can refer to entities in the real world. Research on symbolic development suggests that symbolic understanding requires that children develop dual representational abilities, meaning children need to appreciate that a symbol is an object in itself (i.e., picture of a dog) while also being a representation of something else (i.e., the real dog). Drawing on classic research on symbols and new research on children’s learning from touch screens, we offer the perspective that children’s ability to learn from the touch screen as a symbolic medium depends on the effect of interactivity on children’s developing dual representational abilities. Although previous research on dual representation suggests the interactive nature of the touch screen might make it difficult for young children to use as a symbolic medium, the unique interactive affordances may help alleviate this difficulty. More research needs to investigate how the interactivity of the touch screen affects children’s ability to connect the symbols on the screen to the real world. Given the interactive nature of the touch screen, researchers and educators should consider both the affordances of the touch screen as well as young children’s cognitive abilities when assessing whether young children can learn from it as a symbolic medium

Tinkering With Testing:Understanding How Museum Program Design Advances Engineering Learning Opportunities for Children

Using a design-based research approach, we studied ways to advance opportunities for children and families to engage in engineering design practices in an informal educational setting. 213 families with 5–11-year-old children were observed as they visited a tinkering exhibit at a children’s museum during one of three iterations of a program posing an engineering design challenge. Children’s narrative reflections about their experience were recorded immediately after tinkering. Across iterations of the program, changes to the exhibit design and facilitation provided by museum staff corresponded to increased families’ engagement in key engineering practices. In the latter two cycles of the program, families engaged in the most testing, and in turn, redesigning. Further, in the latter cycles, the more children engaged in testing and retesting during tinkering, the more their narratives contained engineering-related content. The results advance understanding and the evidence base for educational practices that can promote engineering learning opportunities for children

Dynamical characteristics of cirrus clouds from aircraft and radar measurements

Cirrus clouds play an important role in climate and in the development of other types of clouds. Although there are many studies of clouds within the boundary layer, cirrus clouds have been neglected up until the last decade. New tools and in-situ measurements of various physical and dynamical parameters permit us to now study cirrus clouds in much greater detail. Physical and dynamical structures of cirrus clouds were studied in detail by Heymsfield using aircraft measurements. He emphasized the importance of interactions among physical and dynamical processes. Cirrus clouds often exhibit complex physical and dynamical structure. Upper tropospheric flows contain not only coherent structures, but also chaotic movements. The coherent structures (organized movements) transfer significant amounts of heat and momentum while their form, size, and intensity depend strongly on environmental instability. Various dynamical structures including cells, waves, and turbulence are studied in order to understand cirrus cloud formation and development

Comparison of cloud microphysical parameters derived from surface and satellite measurements during FIRE phase 2

Cloud microphysical properties are an important component in climate model parameterizations of water transport, cloud radiative exchange, and latent heat processes. Estimation of effective cloud particle size, liquid or ice water content, and optical depth from satellite-based instrumentation is needed to develop a climatology of cloud microphysical properties and to better understand and model cloud processes in atmospheric circulation. These parameters are estimated from two different surface data sets taken at Coffeyville, Kansas, during the First ISCCP Regional Experiment (FIRE) Phase-2 Intensive Field Observation (IFO) period (November 13 - December 7, 1991). Satellite data can also provide information about optical depth and effective particle size. This paper explores the combination of the FIRE-2 surface and satellite data to determine each of the cloud microphysical properties