Children’s use of subtraction by addition on large single-digit subtractions

Subtractions of the type M − S = ? can be solved by various strategies, including subtraction by addition. In this study, we investigated children’s use of subtraction by addition by means of reaction time analyses. We presented 106 third to sixth graders with 32 large non-tie single-digit problems in both subtraction (12 − 9 = .) and addition format (9 + . = 12). We examined the fit of three regression models, which represented the consistent use of direct subtraction, of subtraction by addition and of flexibly switching between both strategies based on the relative size of the subtrahend. Findings revealed that children did not switch flexibly between the two strategies, as adults do, but that they rely on direct subtraction for problems presented in subtraction format and on subtraction by addition for problems in addition format. We end with the major theoretical, methodological and educational implications of these results.     

Towards an integrated model for developing sustainable assessment skills

One of the goals of current education is to ensure that graduates can act as independent lifelong learners. Graduates need to be able to assess their own learning and interpret assessment results. The central question in this article is how to acquire sustainable assessment skills, enabling students to assess their performance and learning throughout life, and preparing them to meet their own future learning needs. This article presents an integrated model for developing sustainable assessment skills, consisting of three components: conditions necessary for the development of sustainable assessment skills, elements of sustainable assessment and instructional methods for guiding students in the development of sustainable assessment skills. The article concludes with suggestions for future research to further develop the proposed model.     

Data-driven estimates of global nitrous oxide emissions from croplands

Croplands are the single largest anthropogenic source of nitrous oxide (N₂O) globally, yet their estimates remain difficult to verify when using Tier 1 and 3 methods of the Intergovernmental Panel on Climate Change (IPCC). Here, we re-evaluate global cropland-N₂O emissions in 1961–2014, using N-rate-dependent emission factors (EFs) upscaled from 1206 field observations in 180 global distributed sites and high-resolution N inputs disaggregated from sub-national surveys covering 15593 administrative units. Our results confirm IPCC Tier 1 default EFs for upland crops in 1990–2014, but give a ∼15% lower EF in 1961–1989 and a ∼67% larger EF for paddy rice over the full period. Associated emissions (0.82 ± 0.34 Tg N yr^–1) are probably one-quarter lower than IPCC Tier 1 global inventories but close to Tier 3 estimates. The use of survey-based gridded N-input data contributes 58% of this emission reduction, the rest being explained by the use of observation-based non-linear EFs. We conclude that upscaling N₂O emissions from site-level observations to global croplands provides a new benchmark for constraining IPCC Tier 1 and 3 methods. The detailed spatial distribution of emission data is expected to inform advancement towards more realistic and effective mitigation pathways.     

A multifactorial injury prevention intervention reduces injury incidence in Physical Education Teacher Education students

Physical Education Teacher Education (PETE) students are at considerable risk for non-contact sports injuries of the lower extremities. Multifactorial injury prevention interventions including exercises have been successful in sports populations, but no such study has ever been performed in PETE students. This study investigated the efficacy of a multifactorial injury prevention intervention on injury incidence reduction in PETE students. PETE students in the intervention group (n = 154) and in the control group (n = 189) registered sports injuries prospectively. The intervention lasted one academic year and consisted of an injury awareness programme and preventive strategies, implemented by the PETE sports lecturers. Differences in injury incidence between the intervention and control group were tested by Poisson regression Wald tests. There was a trend towards significantly lower incidence rate (2.18 vs. 2.73; p = 0.061) in the intervention group compared with the control group. Students in the intervention group had significantly less acute, first-time and extracurricular injuries. The largest reduction was observed for injuries during unsupervised practice sessions. A multifactorial injury prevention intervention embedded into a regular PETE programme is a promising and feasible strategy to prevent injuries in PETE students. Further research is needed to investigate whether the results may be generalised to other PETE programmes.     

Identifying profiles of actual and perceived motor competence among adolescents: associations with motivation,physical activity,and sports participation

The present study identified adolescents’ motor competence (MC)-based profiles (e.g., high actual and low perceived MC), and accordingly investigated differences in motivation for physical education (PE), physical activity (PA) levels, and sports participation between profiles by using regression analyses. Actual MC was measured with the Körperkoordinationstest für Kinder. Adolescents (n = 215; 66.0% boys; mean age = 13.64 ± .58 years) completed validated questionnaires to assess perceived MC, motivation for PE, PA-levels, and sports participation. Actual and perceived MC were only moderately correlated and cluster analyses identified four groups. Two groups of overestimators (low – overestimation, average – overestimation) were identified (51%), who particularly displayed better motivation for PE when compared to their peers who accurately estimated themselves (low – accurate, average – accurate). Moreover, adolescents with low actual MC, but high perceived MC were significantly more active than adolescents with low actual MC who accurately estimated themselves. Results pointed in the same direction for organised sports participation. Underestimators were not found in the current sample, which is positive as underestimation might negatively influence adolescents’ motivation to achieve and persist in PA and sports. In conclusion, results emphasise that developing perceived MC, especially among adolescents with low levels of actual MC, seems crucial to stimulate motivation for PE, and engagement in PA and sports.     

Musculoskeletal injuries in physical education versus non-physical education teachers: a prospective study

Physical education (PE) teachers have a physically demanding job, putting them at a considerable risk for musculoskeletal injuries. To structurally develop tailored injury prevention programmes for PE teachers, a clear understanding of the extent, characteristics and underlying factors of their musculoskeletal injuries compared to referents is necessary. Therefore, the current study prospectively followed 103 PE teachers and 58 non-PE teachers, who registered musculoskeletal injuries and time of exposure to sports participation during one school year. Pearson χ²-tests and independent samples t-tests determined significant differences between PE and non-PE teachers regarding demographics and variables possibly related to injury occurrence. PE teachers had 1.23 and non-PE teachers 0.78 injuries/teacher/school year. This difference was significantly different after adjustment for hours spent weekly on intracurricular teaching during the career and for injury history during the preceding six months (P = 0.009; OR = 0.511; 95% CI = 0.308–0.846). PE teachers’ most affected body parts were the knee and the back. PE teachers had a more extensive injury history (P < 0.001), a higher work- (P < 0.001) and sport index (P < 0.001), practiced more sports (P < 0.002) and taught more extracurricular sports (P = 0.001). Future injury prevention programmes should take account for the great injury history and heavy physical load in PE teachers.