Pengembangan Perangkat Pembelajaran Matematika pada Pokok Bahasan Lingkaran Menggunakan Pendekatan Pmri dan Aplikasi Geogebra

This study aims to produce the learning of mathematics on the subject of the circle using PMRI approach and Applications Geogebgra valid and practical as well as to determine the potential effects of such devices on student learning outcomes. Based on the results obtained by the prototype development of learning tools, design implementation of learning, student worksheets, and learning about the test results are valid and practical. Validity fulfilled qualitatively by the validator. Meanwhile, practicality demonstrated by experts / practitioners have expressed learning tools developed can be applied to the junior high school students, in addition to the appropriate implementation of phase one to one and small group, all students can use learning device properly. From observations of student learning activities, the results of students' answers, it appears that the learning device developed has potential effect to improve student math skills. Besides of interviews on the field test stage, most students said that learning device by using GeoGebra application for a given subject interesting circle, and may spur enthusiasm in learning mathematics Keyword: development, learning materials, PMRI approach, GeoGebra

Pengembangan Website Pembelajaran Matematika Realistik Untuk Siswa Sekolah Menengah Pertama

This study aims to develop an internet-based mathematics learning environment, especially for junior high school students who realized through the development of realistic mathematics learning website that is valid, practical, and effective. But in this article the discussion is focused on validity and practicality. The method used in this study is development research method with type of formative research covering phase of analysis, developing and formative evaluation. Techniques of collecting data in the form of documentation, walk through, tests, observations, and interviews. The data analysis technique used is descriptive qualitative. Validity fulfilled qualitatively by the validator. Practical criteria are met if they fulfill two things; (1) the experts state that what is developed can be applied, and (2) the reality shows that what is developed is applicable. The result obtained is a prototype of a valid and practical mathematics learning website Keyword: website, learning, mathematics, realistic

Pembelajaran Arias dengan Setting Kooperatif dalam Pembelajaran Geometri Analitik Bidang

The purpose of this study is to know the improvement in student learning outcomes taught through ARIAS learning with cooperative settings in learning Analytical Geometry Fields. This study uses a research design type 0ne-Shot Case Study. The research subjects were lecturers and students of the second semester of the Department of Mathematics Education Unima, academic year 2018/2019, which succeeded 25 students. Data obtained through the results of the test form description. Obtained the average results of student learning outcomes using this learning model is 82 with a maximum value of 95, while the results of inferential statistical analysis obtained results t_hitung= 12,3494 > t_tabel=1,708, with a real level (∝) = 0.05. This means the average learning outcomes are more than 62.5 which is a benchmark of graduation. The results showed that using the ARIAS learning model with cooperative settings in learning Geometry Analytic Fields can improve student learning outcome

Water-sediment exchanges control microbial processes associated with leaf litter degradation in the hyporheic zone: a microcosm study

The present study aimed to experimentally quantify the influence of a reduction of surface sediment permeability on microbial characteristics and ecological processes (respiration and leaf litter decomposition) occurring in the hyporheic zone (i.e. the sedimentary interface between surface water and groundwater). The physical structure of the water-sediment interface was manipulated by adding a 2-cm layer of coarse sand (unclogged systems) or fine sand (clogged systems) at the sediment surface of slow filtration columns filled with a heterogeneous gravel/sand sedimentary matrix. The influence of clogging was quantified through measurements of hydraulic conductivity, water chemistry, microbial abundances and activities and associated processes (decomposition of alder leaf litter inserted at a depth of 9 cm in sediments, oxygen and nitrate consumption by microorganisms). Fine sand deposits drastically reduced hydraulic conductivity (by around 8-fold in comparison with unclogged systems topped by coarse sand) and associated water flow, leading to a sharp decrease in oxygen (reaching less than 1 mg L(-1) at 3 cm depth) and nitrate concentrations with depth in sediments. The shift from aerobic to anaerobic conditions in clogged systems favoured the establishment of denitrifying bacteria living on sediments. Analyses performed on buried leaf litter showed a reduction by 30% of organic matter decomposition in clogged systems in comparison with unclogged systems. This reduction was linked to a negative influence of clogging on the activities and abundances of leaf-associated microorganisms. Finally, our study clearly demonstrated that microbial processes involved in organic matter decomposition were dependent on hydraulic conductivity and oxygen availability in the hyporheic zone

Faunal response to benthic and hyporheic sedimentation varies with direction of vertical hydrological exchange

1. Sedimentation and clogging of benthic and hyporheic zone substrates is increasingly being recognised as one of the greatest threats to the ecological integrity of riverine ecosystems globally. This ex-situ study examined the influence of sedimentation (benthic and hyporheic) and pattern of hydrological exchange on the vertical distribution of the freshwater shrimp Gammarus pulex within the experimental substrates of running water mesocosms. 2. Six sediment treatments representing a continuum from a clean gravel substratum through to heavy sediment loading of both benthic and hyporheic substrates were used to examine the distribution of G. pulex in relation to the direction of hydrological exchange (downwelling, upwelling and no exchange). 3. The vertical distribution of fauna varied significantly for both sediment treatment and pattern of hydrological exchange. There was a significant interaction between the two effects indicating that the effect of sedimentation varied depending on the pattern of vertical hydrological exchange

A cost-effective method to quantify biological surface sediment reworking

We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g., luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2.d-1, such as triggered by intermediate density (774 m-2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2.d-1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution

Benzo(a)pyrene inhibits the role of the bioturbator Tubifex tubifex in river sediment biogeochemistry

International audienceThe interactions between invertebrates and micro-organisms living in streambed sediments often play key roles in the regulation of nutrient and organic matter fluxes in aquatic ecosystems. However, benthic sedi- ments also constitute a privileged compartment for the accumulation of persistent organic pollutants such as PAHs or PCBs that may affect the diversity, abundance and activity of benthic organisms. The objective of this study was to quantify the impact of sediment contamination with the PAH benzo(a)pyrene on the in- teraction between micro-organisms and the tubificid worm, Tubifex tubifex, which has been recognized as a major bioturbator in freshwater sediments. Sedimentary microcosms (slow filtration columns) contaminated or not with benzo(a)pyrene (3 tested concentrations: 0, 1 and 5 mg kg−1) at the sediment surface were in- cubated under laboratory conditions in the presence (100 individuals) or absence of T. tubifex. Although the surface sediment contaminations with 1 mg kg−1 and 5 mg kg−1 of benzo(a)pyrene did not affect tubificid worm survival, these contaminations significantly influenced the role played by T. tubifex in biogeochemical processes. Indeed, tubificid worms stimulated aerobic respiration, denitrification, dehydrogenase and hydrolytic activities of micro-organisms in uncontaminated sediments whereas such effects were inhibited in sediments polluted with benzo(a)pyrene. This inhibition was due to contaminant-induced changes in bioturbation (and especially bio-irrigation) activities of worms and their resulting effects on microbial processes. This study reveals the importance of sublethal concentrations of a contaminant on ecological processes in river sediments through affecting bioturbator-microbe interactions. Since they affect microbial processes involved in water purification processes, such impacts of sublethal concentrations of pollutants should be more often considered in ecosystem health assessment

OPTIMIZING ELEMENTARY TEACHERS' ABILITY IN DESIGNING REALISTIC AND ICT-BASED MATHEMATICS LEARNING

Proses pembelajaran menjadi salah satu tantangan yang dihadapi mitra sekolah dasar di Kecamatan Modayag Kabupaten Bolaang Mongondow Timur. Pengajaran matematika pada dasarnya masih berpusat pada guru, berdasarkan observasi yang dilakukan di SD Negeri 1 Purwerejo dan SD Negeri 1 Purwerejo Timur. Selain itu, proses pembelajaran memberikan lebih banyak pengetahuan dari pengajar kepada peserta didik. Kebanyakan komunikasi masih bersifat sepihak. Selain itu, matematika biasanya diajarkan kepada siswa secara abstrak tanpa ada kaitannya dengan situasi nyata. Selain itu, ia mengklaim permasalahan ini muncul di sebagian besar SD di Kecamatan Modayag berdasarkan percakapan dengan salah satu kepala sekolah. Mengingat rincian ini dan hasil diskusi mitra, diperlukan inovasi pembelajaran. Untuk membangkitkan minat siswa terhadap matematika, produk baru harus menjembatani mata pelajaran tersebut dan pengalaman mereka sehari-hari. Salah satu konsep yang dapat digunakan adalah Pendidikan Matematika Realistis Indonesia (PMRI). Untuk menerapkan pembelajaran matematika nyata di kelas, kegiatan sains dan teknologi untuk masyarakat diciptakan melalui lokakarya, bahan ajar, dan dukungan guru. PKM dimulai dengan pembelajaran PMRI, kemudian ujian terhadap peserta didik, kurikulum, sumber daya, media, dan skenario dunia nyata terkait. Pelatihan dilaksanakan di SD Negeri 1 Purwerejo Timur dan dilanjutkan dengan pendampingan pembuatan bahan ajar berbasis PMRI. Hasil yang diperoleh dari kegiatan ini adalah: Guru di sekolah mitra memahami prinsip dan ciri pembelajaran PMRI; (1) Aksesibilitas sumber daya pembelajaran, antara lain RPP, LAS, dan soal-soal ujian yang berasal dari pembelajaran PMRI, (2) Media dan perangkat lunak yang tersedia untuk menggambarkan ide-ide matematika yang umum