Various studies showed that there are some points which affect students’ achievement; one of them is mathematics self-efficacy. Self-efficacy is feeling, trust, and confidence of affective behavior of students toward their ability. In learning process, the students find obstacles in solving their problem such as relating one representation to another representation. Previous studies indicated that students’ achievement of mathematical representation ability have obstacles because the students did not understand relationship between concepts, ideas, and materials to be represented. The other studies claimed that the higher students’ self-efficacy, the higher mathematical multiple representation ability (MMRA). It means that self-efficacy has positive correlation with mathematic ability. This article will discuss about role of mathematics self-efficacy toward ability achievement of mathematical multiple representation ability (MMRA) in solving mathematics problem in order to increase students’ achievement.

Teknik pemisahan residu gliserol dari MDAG yang diproduksi dengan cara gliserolisis paling efektif adalah dengan menggunakan Short Path Distillation (SPD) atau distilasi molekuler yang masih merupakan teknologi mahal dan canggih sehingga sulit untuk diaplikasikan secara luas.  Ekstraksi dan fraksinasi menggunakan pelarut merupakan teknik pemisahan residu gliserol yang lain, teknik ini telah dikembangkan oleh beberapa peneliti, tetapi panjangnya prosedur pengerjaan dan adanya kemungkinan sisa pelarut dalam produk akhir menjadi kendala tersendiri. Penelitian ini mempelajari pemisahan residu gliserol dari MDAG hasil proses gliserolisis melalui proses demulsifikasi pembentukan krim dengan atau tanpa penambahan larutan pada berbagai suhu minyak sehingga terbentuk krim dan skim yang mudah dipisahkan. Hasil penelitian menunjukan bahwa pemisahan gliserol dari sistem emulsinya, dengan metode demulsifikasi pembentukan krim paling efektif jika dilakukan pada suhu tinggi (65oC) karena pada suhu tersebut minyak memiliki densitas yang paling rendah dan akan berada pada bagian atas dalam reaktor pemisah residu gliserol saat sistem emulsinya mengalami instabilitas (creaming) sehingga lebih mudah dipisahkan.  Pemurnian MDAG dengan cara demulsifikasi pembentukan krim tanpa penambahan air hanya mampu menurunkan kandungan gliserol maksimal sebesar 37%; sisa gliserol yang masih berada dalam produk akhir sekitar 9.17% dirasakan masih terlalu tinggi untuk dapat dikatakan sebagai MDAG murni.  Pemurnian dengan cara demulsifikasi pembentukan krim dengan penambahan air suling menghasilkan MDAG dengan kandungan gliserol berkisar aintara 4.05—6.59%.  Pemurnian dengan cara demulsifikasi pembentukan krim dengan penambahan larutan elektrolit menghasilkan MDAG dengan kandungan gliserol berkisar antara 1.94—1.95% (tanpa proses sentrifugasi) dan 0.02-0.05% (dengan sentrifugasi 2000 rpm selama 5 menit).

The purpose of this study is to analize the improving of mathematical communication skills’s students, the learning acktivities of student and student’s response at Realistic Mathematics (RME) learning.  The research is held at MTs.S Syamsudduha in 2018-2019 years, which using quasi experiment with a quantitative approach. This study used two samples, they are experiment’s class as treatment class consists of 34 students and control’s class which  not give the treatment consists of 36 students which the sample was taken in this research used the technique sampling purposive. This data was obtained with test technique and observation sheet. Data is analyzed with t test using SPSS 18, the result show that there is an increasing of mathematical communication skills of student on statistical study with the Realistic Mathematics Education (RME) learning. This shows that value of n-gain on student’s mathematical communication skill for experiment’s class is 0,49 and control’s class is 0,17 with significant 0,000 < 0,05, thats mean there is an increasing in the learning process. So, RME learning can improve student’s mathematical communication skills of  students better than students who is taught by conventional learning.

This study aims to determine the significant effect of WhatsApp based on Google Classroom and Google Meet with the implementation of the inquiry learning model in physics learning on student learning outcomes. The research was conducted during the Covid-19 pandemic with a DARING learning process, the method used was the pre-experimental method with one group pretest-posttest design. This research was conducted at SMA Negeri 1 Suwawa in the academic year 2020/2021 using saturated sampling technique and random selection of classes, obtained by students of class XI IPA 1 as an experimental class, class XI IPA 3 as replication class 1, XI IPA 4 as class replication 2 and class XI IPA 2 as replication class 3. The research instrument is in the form of an essay test of 8 numbers on the Dynamics of Rotation and Sturdy Object Balance with a KKM of 73. Based on the results of hypothesis testing, it is known that the t value for each experimental class is replication class 1, replication class 2, and replication class 3 are 4.16, 3.089. , 3.19, 3.386 greater than t table 1.705, 1.739, 1.71, 1.72, it can be concluded that there is a significant positive effect of treatment. Based on the analysis of the N-Gain and the effect size, the N-Gain value for the four classes, respectively, is 0.61, 0.59.0.59, and 0.62 in the medium category, for the effect size value is 1.9 with strong effect interpretation. This shows that there is consistency in the treatment given to student learning outcomes.

Mengingat munculnya beberapa peraturan baru di bidang lingkungan hidup, maka para pemangku kepentingan (stakeholder) perlu memahami dengan baik regulasi tersebut. Oleh karena itu artikel ini bertujuan untuk memberikan pemahaman praktis tentang beberapa nomenklatur baru serta mekanisme penyusunan dan penilaian dokumen lingkungan hidup untuk mendapatkan persetujuan lingkungan yang tertera pada sejumlah regulasi baru. Terbitnya PP Nomor 22 tahun 2021 mengharuskan diterbitkan beberapa PerMenLHK baru. Terdapat beberapa persyaratan baru yang wajib dipenuhi dalam pengajuan permohonan persetujuan lingkungan, yakni: Surat pernyataan bahwa kegiatan yang diajukan masih dalam tahap perencanaan, Persetujuan Teknis (Pertek), Persetujuan awal terkait rencana usaha/kegiatan, Bukti kesesuaian lokasi rencana usaha/kegiatan dengan rencana tata ruang. Proses penilaian dokumen lingkungan juga mengalami beberapa perubahan yang harus disesuaikan dengan regulasi baru tersebut. Kewenangan penilaian dokumen lingkungan hidup didasarkan atas kewenangan penerbitan perizinan berusaha serta dibentuknya Tim Uji Kelayakan (TUK) yang menggantikan peran Komisi Penilai Amdal (KPA).