Minggu, 10 Mei 2020

Assessment Of Learning


Assessment Of Learning

1.      Definition of Learning Assessment
From the point of view of language, judgment is defined as the process of determining the value of an object. To be able to determine a value or price of an object requires the size or criteria. For example, to be able to say good, moderate, less, there needs to be a clear measure of how good, medium, and less. The measure is called the criterion. From this understanding, it can be said that the characteristics of assessment are the existence of the object or program being assessed and the existence of criteria as a basis for comparing what is achieved with the criteria that must be achieved. Comparison can be absolute, it can also be relative.
Comparison is absolute meaning that the results of the comparison describe the position of the object being evaluated in terms of applicable criteria. While the relative comparison means the result of the comparison is more describing the position of an object that is valued against other objects based on the same criteria. Thus, the core assessment is the process of determining the value of a particular object based on certain criteria. The process of giving value takes place in the form of interpretation which ends with judgment. Interpretation and judgement is a theme of assessment that implies a comparison between criteria and reality in the context of a particular situation. On that basis, in the assessment activities there are always objects / programs that are assessed, there are criteria, and there are interpretations / judgments.
Assessment of learning outcomes is the process of assigning grades to learning outcomes achieved by students with certain criteria. This implies that the object judged is the result of student learning. Student learning outcomes are essentially change in behavior. Behavior as a result of learning in a broad sense covers the fields of cognitive, affective, and psychomotor. Therefore, in the assessment of learning outcomes the formulation of abilities and behaviors desired by students (competence) becomes an important element as a basis and reference for assessment. Assessment of the learning process is an effort to give value to teaching and learning activities carried out by students and teachers in achieving teaching objectives.

2.      Learning Assessment Function
The purpose of learning is essentially a change in behavior in students. Therefore, the assessment should be examined to what extent changes in student behavior have occurred through the learning process. For example by making changes in teaching strategies, providing guidance and learning assistance to students. In other words, the results of the assessment are not only useful for knowing whether changes in student behavior have been achieved, but also as feedback for efforts to improve the learning process.
In this assessment seen the extent to which the effectiveness of the learning process in seeking changes in student behavior. Therefore, the assessment of learning outcomes and processes are interrelated with each other because the learning outcomes achieved by students are a result of the learning process that they go through (their learning experiences). In line with the above understanding, the evaluation functions as follows:
a.      Tool to find out whether learning objectives are achieved. With this function then the assessment must refer to the formulations of learning objectives as a translation of the subject competencies.
b.      Feedback for improving the teaching and learning process. Improvements might be made in terms of learning objectives, student learning activities or experiences, learning strategies used by the teacher, learning media, etc.
c.      The basis for compiling reports on student learning progress to his parents. In the report, students' ability and study skills were expressed in various fields of study or subjects in the form of achievement values.

3.      Purpose of Learning Assessment
In line with the assessment function above, the purpose of the assessment of learning outcomes is to:
a.      Describe students' learning skills so that their strengths and weaknesses can be identified in various fields of study or subjects they take. By describing the skills, it can also be seen the position of the ability of students compared to other students
b.      Knowing the success of the education and learning process in school, in aspects of intellectual, social, emotional, moral, and skills, namely how far the effectiveness in changing the behavior of students towards the expected educational goals. The success of education and learning is important, considering its role as an effort to humanize or civilize humans, in this case students to become qualified human beings
c.      Determine the follow-up of the results of the assessment, namely to make improvements and improvements in terms of education and learning programs and their implementation strategies. Failure of students in learning outcomes they achieve should not be seen as lacking solely in students themselves, but can also be caused by learning programs that are given to them or by strategic mistakes in executing these programs. For example, inaccuracies in choosing and use teaching methods and learning aids
d.      Provide accountability (accountability) from the school to the parties concerned. The parties in question include the government, the community, and parents of students. In accounting for the results it has achieved, the school reports various strengths and weaknesses in the implementation of the education system and the obstacles it faces. Reports are submitted to interested parties, for example the local education office through officers who handle it. While accountability to the community and parents is conveyed through student learning progress reports (report cards) at the end of each program/semester

4.      Principles of Learning Assessment
In addition to the purpose and function of assessment, teachers must also understand the principles of assessment. The principles of assessment referred to include the following:
a.      Assessment of learning outcomes should be an integral part of the learning process. This means that every teacher carrying out the learning process he must carry out assessment activities. The intended evaluation is formative assessment. There is no learning process without assessment. Thus the progress of student learning can be known and the teacher can always improve the quality of the learning process carried out.
b.      Assessment of learning outcomes should be clearly designed what abilities should be assessed, the material or content of the teaching material being tested, the assessment tools to be used, and the interpretation of the results of the assessment. As a benchmark or signs in designing assessment of learning outcomes is a curriculum that applies primarily the objectives and competencies of subjects, the scope of the content or teaching material and guidelines for its implementation.
c.      The assessment must be carried out comprehensively, meaning that the abilities measured include cognitive, affective and psychomotor aspects. In cognitive aspects include: knowledge, understanding, application, analysis, synthesis, and evaluation proportionally.
d.      Assessment tools must be valid and reliable. Valid means measuring what should be measured (accuracy). Reliability means that the results obtained from the assessment are consistent or consistent.
e.      Assessment of learning outcomes should be followed by no further. Assessment data is very useful for teachers as material to perfect learning programs, improve learning weaknesses, and tutoring activities for students who need them.
f.       Assessment of learning outcomes must be objective and fair so that they can describe the actual abilities of students.

Indonesian Education Ministry, 2008

Senin, 13 Juni 2016

Translation I: initiation
Like amino acid activation (see p. 248), protein biosynthesis (translation) takes place in the cytoplasm. It is catalyzed by complex nucleo protein particles, the ribosomes,and mainly requires GTP to cover its energy requirements.
A. Structure of the eukaryotic ribosome
Ribosomes consist of two sub units of different size, made up of ribosomal RNA (rRNA) and nearly 80 proteins(the number of proteins applies to rat liver ribosomes). It is customary to give the sedimentation coeficients (see p. 200) of ribosomes and their components instead of their masses. For example, the eukaryotic ribosome has a sedimentation coefficient of 80 Svedberg units (80 S), while the sedimentation coeficients of its sub units are 40 S and 60 S (S values are not additive).
The smaller 40 S sub unit consists of one molecule of 18 S rRNA and 33 protein molecules. The larger 60 S sub unit contains three types of rRNA with sedimentation coeficients of  5S, 5.8S, and 28S and 47 proteins. In the presence of mRNA, the sub units assemble to form the complete ribosome, with a mass about 650 times larger than that of a hemoglobin molecule. The arrangement of the individual components of a ribosome has now been determined for prokaryotic ribosomes. It is known that filamentous mRNA passes through a cleft between the two sub units near the characteristic “horn” on the small sub unit. tRNAs also bind near this site. The illustration shows the size of at RNA molecule for comparison. Prokaryotic ribosomes have a similar structure, but are somewhat smaller than those of eukaryotes (sedimentation coeficient 70 S for the complete ribosome, 30 S and 50 S for the subunits). Mitochondrial and chloroplast ribosomes are comparable to prokaryotic ones.
B. Polysomes
In cells that are carrying out intensive protein synthesis, ribosomes are often found in a linear arrangement like a string of pearls; these are known as polysomes. This arrangement arises because several ribosomes are translating a single mRNA molecule simultaneously.  The ribosome first binds near the start codon (AUG; see p. 248) at the 5 end of the mRNA (top). During translation, the ribosome moves in the direction of the 3 end until it reaches a stop codon (UAA, UAG, or UGA). At this point, the newly synthesized chain is released, and the ribosome dissociates again into its two
subunits.
C. Initiation of translation in E. coli
Protein synthesis in prokaryotes is in principle the same as in eukaryotes. However, as the process is simpler and has been better studied in prokaryotes, the details involved in translation are discussed here and on p. 252 using the example of the bacterium Escherichia coli. The first phase of translation, initiation,involves several steps. First, two proteins,initiation factors IF–1 and IF–3, bind to the 30 S
subunit (1). Another factor, IF–2, binds as a complex with GTP (2). This allows the subunit to associate with the mRNA and makes it possible for a special tRNA to bind to the start codon (3). In prokaryotes, this starter tRNA carries the substituted amino acid Nformylmethionine(fMet). In eukaryotes, it carries an unsubstituted methionine. Finally, the 50 S subunit binds to the above complex (4). During steps 3 and 4, the initiation factors are released again, and the GTP bound to IF–2 is hydrolyzed to GDP and Pi.
In the 70 S initiation complex, formylmethionine tRNA is initially located at a binding site known as the peptidyl site (P). A second  binding site, the acceptor site (A),is not yet occupied during this phase of translation. Sometimes, a third tRNA binding site is defined as an exit site (E),from which uncharged tRNAs leave the ribosome again (see p. 252;not shown)




Kamis, 05 Mei 2016



PEMBUATAN KALSIUM OKSALAT HIDRAT

TUJUAN
Mempelajari pembuatan kalsium oksalat hidrat dengan metode pengendapan
TEORI
Endapan oksalat hidrat umumnya berwarna putih. Dalam laboratorium, senyawa oksalat golongan IIA dapat dengan mudah dibuat dengan reaksi pengendapan yang terjadi disekitar pH 5. Proses pengendapan dalam analisa kuantitatif antara lain digunakan untuk memisahkan suatu zat dari zat yang lainnya, yang merupakan dasar titrasi pengendapan. Endapan yang ideal adalah endapan yang sangat sukar larut dalam medium yang digunakan, murni atau mudah dimurnikan sebelum penimbangan dan merupakan kristal yang kasar. Untuk memperoleh endapan yang ideal, maka harus diperhatikan faktor yang mempengaruhi endapan seperti:
·         Derajat kelewat jenuh
·         Jenis presipitan
·         Cara penambahan presipitan
·         Suhu
·         Pendiaman endapan (degestion)
Reaksi pengendapan yang terjadi disekitar pH 5 yaitu:


Pada proses pembentukan kalsium oksalat hidrat prinsipnya yaitu reaksi ion logam dengan C2O42-, dimana pada percobaan ini akan digunakan urea yang berfungsi sebagai bahan dasar untuk mendapatkan endapan secara bertahap. Pada pembuatan kalsium oksalat hidrat dengan metode pengendapan ini, akan terdapat pengotor pada endapan yang terbentuk. Beberapa proses yang dapat mengakibatkan pengotoran endapan yaitu:
a.       Ko-presipitasi
Adalah ikut mengendapnya dua atau lebih zat pada waktu yang sama. Kalau dalam arti khusus yaitu ikut mengendapnya satu atau lebh zat asing bersama endapan dari komponen zat uji.
b.      Larutan padat
Dua zat padat larut satu sama lain membentuk padatan. Keduanya dapat membentuk kristal yang campuran dimana zat yang satu berada dalam kisi kristal yang lain.
c.       Adsorbsi
Pada permukaan dari partikel endapan, terdapat gugusan aktif yang dapat menarik dan mengikat zat yang sebenarnya tidak mengendap.

d.      Oklusi
Adalah ikut mengendapnya kotoran yang terperangkap dibagian dalam dari partikel.
e.      Pospresipitasi
Pada pospresipitasi, pendapat semula dikotori oleh endapan zat lain yang terbentuk kemudian. Pengotoran ini terjadi karena kontaminasi merupakan larutan lewat jenuh. Misalnya pada pengendapan kalsium sebagai oksalat dari larutan yang menggunakan magnesium. Bila kalsium oksalat tidak segera disaring setelah pengendapan, magnesium oksalat terserap pada permukaan kalsium oksalat, maka ia tidak dapat larut kembali.
Oleh karena senyawa oksalat golongan IIA merupakan garam yang sedikit bersifat asam, maka kelarutannya akan bertambah meningkat dengan naiknya konsentrasi ion hidrogen.
Metode yang digunakan disini adalah “homogeneus precipitation”. Dimana proses pengendapan tidak dilakukan secara langsung tapi dilakukan secara bertahap, oleh karena itu digunakan urea sebagai penahannya. Senyawa-senyawa oksalat dari ion-ion logam pada golongan IIA ini umumnya tidak larut dalam larutan netral atau sedikit asam.
Pada pembuatan kalsium oksalat hidrat ini, kalsium direaksikan dengan C2O42-, dimana kalsium ini adalah logam putih perak yang agak lunak, ia melebur pada suhu 8450C. kalsium membentuk kation kalsium (II), Ca2+ dalam larutan-larutan air.