Teacher Candidates' Perceptions About Grading and Constructivist Teaching

The Survey of Assessment Beliefs (SAB) was developed to measure teacher candidates' perceptions about grading practices. After piloting, the SAB was administered to 222 teacher candidates at a large northeastern urban university, along with a measure of their beliefs about teaching. Candidates were found to support many grading practices not recommended by professional standards. Support for grading practices that deviate from professional recommendations was positively associated with support for constructivist approaches. Significant differences were found in grading and teaching attitudes between elementary and secondary education teacher candidates. Teacher candidates became more moderate in endorsing nonstandard grading practices following coursework in classroom assessment but on average maintained a tendency to approve academically enabling grading practices. This study provides empirical evidence about possible areas of tension between constructivist learning theory and principles of educational measurement, and it helps classroom assessment teachers understand the needs of their target audiences.     

Development Without Learning?

It is usually assumed that for cognitive development to occur, children need to receive feedback about the success of their endeavours. Such views are implicitly contained in the design of most educational programmes, especially those that are based on computer‐assisted learning. Two studies are reported which challenge these assumptions. The studies investigate Karmilojf‐Smith's ideas about the cognitive processes underlying the development of the ability to balance beams on a fulcrum. Karmiloff‐Smith suggests that at a certain and limited phase of development, children may largely ignore the information from feedback and development will occur due to internal cognitive reorganisation. Our findings provide some support for this view in that at this phase of development no difference was found between children who did and did not receive feedback about success.     

Vimentin networks at tunable ion-concentration in microfluidic drops

The structure and function of biological systems, for example, cells and proteins, depend strongly on their chemical environment. To investigate such dependence, we design a polydimethylsiloxane-based microfluidic device to encapsulate biological systems in picoliter-sized drops. The content of each individual drop is tuned in a defined manner. As a key feature of our method, the individual chemical composition is determined and related to the drop content. In our case, the drop content is imaged using microscopy methods, while the drops are immobilized to allow for long-time studies. As an application of our device, we study the influence of divalent ions on vimentin intermediate filament networks in a quantitative way by tuning the magnesium concentration from drop to drop. This way we are able to directly image the effect of magnesium on the fluorescently tagged protein in a few hundreds of drops. Our study shows that with increasing magnesium concentration in the drops, the compaction of the networks becomes more pronounced. The degree of compaction is characterized by different morphologies; freely fluctuating networks are observed at comparatively low magnesium concentrations of 5–10 mM, while with increasing magnesium concentration reaching 16 mM they develop into fully aggregated networks. Our approach demonstrates how a systematic study of interactions in biological systems can benefit from the exceptional controllability of microfluidic methods.