Letters to the Editor
Teaching the Constitution of Matter
MaЕ‚gorzata NodzyЕ„ska, Jan Rajmund PaЕ›koВлезте в системата, за да прочетете пълната статия
Education: Theory & Practice
Encouraging Higher Level Questioning by the Use of Teaching Technology
Резюме. Aiming to analyze learnersпїЅ participation and their readiness to formulate higher level questions under the influence of the teaching technology, a research was conducted in the subject of civic education. Research population sample comprised 126 pupils and the data was collected through a survey conducted amongst the pupils. In order to motivate the pupils to ask higher level questions, the overhead projector, television and the computer were used. Research findings show the tendency of the increase of pupilsпїЅ motivation for formulating questions that develop higher level thinking and reflection in responding as a result of the use of the teaching technology, but, at the same time, they indicate the low level of their application in the teaching practice. The situation of poor application of questioning strategies which stimulate the development of higher level thinking, as well as the lack of use of the teaching technology has to be changed in order that the teaching process changes and educational needs are successfully realized.
Keywords: higher level thinking, pupilsпїЅ questions, civic education, teaching technology
Hatixhe IsmajliВлезте в системата, за да прочетете пълната статия
Blood Clotting [In Bulgarian]
Резюме. This paper provides a detailed review of hemostasis and blood coagulation. Hemostasis can be divided into four general phases: the vascular phase, endothelium-thrombocyte phase, the coagulation cascade phase and the fibrinolytic phase. The mechanisms involved in each of four phases are discussed. The combined activity of vascular, platelet, and plasma factors is presented. The paper focuses on the regulatory mechanisms which all support the dynamic equilibrium that provides proper blood flow. Hemostatic abnormalities can lead to excessive bleeding or thrombosis.
Keywords: hemostasis, blood coagulation, regulation of blood clotting
M. Radoslavova, A. DragoevaВлезте в системата, за да прочетете пълната статия
Резюме. The lecture demonstration of the decomposition of H2O2 in the presence of Mn(IV) oxide with a proof of the products of the reaction is presented in an entertaining way with the smoking and shrinking water bottle. Designed are several three minutes reaction time presentations, which can demonstrate the reaction rate factors: catalyst, surface area, concentration, and temperature. The materials and the reaction changes can be used for an introduction, or review of some chemistry topics: state and changes of matter, collision theory, activation energy, catalysis, redox reactions, exothermic and decomposition reactions, evaporation, condensation, enthalpy, entropy, classification and recycling of polymers. With a suitable explanation the demonstrations or a part of them can be shown to all grades of students and the general public to inspire science and chemistry in particular.
Keywords: chemistry demonstrations, reaction rate factors, decomposition, exothermic reactions, enthalpy
E. LozanovВлезте в системата, за да прочетете пълната статия
Secondary School Graduation in Bulgaria: Chemistry Exams (2008-2011) [In Bulgarian]
Резюме. This article presents the results of school-leaving examination in Bulgarian secondary school in the subject пїЅChemistry and EnvironmentпїЅ. The data commented cover the period 2008 пїЅ 2011. The paper reveals several difficulties and problems in the existing practice and some recommendations for their overcoming are given.
Keywords: school-leaving examination, matriculation, chemistry, analysis
M. ZamphirovВлезте в системата, за да прочетете пълната статия
43rd International Chemistry Olympiad [In Bulgarian]
Резюме. The paper represents problems (theoretical and practical) of the 43rd International Chemistry Olympiad and the solutions of theoretical problems. Comments of Bulgarian team presentation are given.
Keywords: International Chemistry Olympiad (IChO), practical exam, theoretical problems and solutions
D. Tasheva, P. TsanovaВлезте в системата, за да прочетете пълната статия
The 50th Anniversary of Semiconfuctor Laser [In Bulgarian]
Резюме. Pioneering developments which are related to the invention of laser, including semiconductor laser, 50 years ago are amongst of the most important scientific achievements of the twentieth century. They still have a significant influence on the technical progress of our society. The essential role of whole host of American researchers (Hall, Holonyak, Nathan, Rediker, Kroemer, Hayashi, etc.) and Russian scientists (Basov, Nasledov, Rivkin, Alferov, Popov, etc.) in the development of the semiconductor and laser engineering has been revealed. Retrospection is made to the struggle of ideas and the stages through which various teams of outstanding scientists from leading research laboratories in the USA (General Electric, Lincoln Laboratory, Bell Telephone, IBM) and Russia (Ioffe Physical Technical Institute, Lebedev Physical Institute of the Russian Academy of Sciences) had to pass through. Evidence of the importance of these fundamental inventions is found in the fact that only 50 years have passed since the discovery of laser and so far ten scholars have been awarded the Nobel Prize for research in the development of principles and applications of laser.
Keywords: semiconductor laser, 50 years, double heterostructure laser
L.K. LazovВлезте в системата, за да прочетете пълната статия
New Very Hard Problems of Balancing Chemical Reactions
Резюме. In this article are balanced two new very hard chemical reactions which possess atoms with fractional oxidation numbers. Considered chemical reactions belong to the class of chemical reactions which have unique coefficients. These reactions are balanced by the classical algebraic method. The decision for study of these chemical reactions was made according to the fact that these reactions cannot be balanced by usage of a computer, because to date is not known any software package. A unique way for balancing of this class chemical reactions is the application of mathematical methods. That was the cause that we chose the classical algebraic method for balancing chemical reactions.
Keywords: chemical reactions, balancing
Ice B. RisteskiВлезте в системата, за да прочетете пълната статия
Personalities in Science
Jubilee: Prof. Dr. Boris Galabov [In Bulgarian]
B.V. ToshevВлезте в системата, за да прочетете пълната статия
History and Philosophy of Science
Professor Iwan Nikolov Stranski – The Forgotten Genius [In Bulgarian]
Резюме. Bulgaria has made a significant contribution to world science. Among the biggest Bulgarian scientific achievements is the creation of the theory of crystal growth and the development of Bulgarian physico-chemical scientific school. The article presents the life and work of Professor Ivan Nikolov Stransky (1896-1979), founder of this scientific school, which continues to give scientific fruits today. In the background of the paper are author’s reminiscences about his meetings and talks with the famous Bulgarian-German scientist Iwan Stranski.
Keywords: Iwan Stranski, crystal growth, University of Sofia, German scientists
Christo N. NanevВлезте в системата, за да прочетете пълната статия
Information about the Science Programmes at the University of Sofia: Faculty of Biology [In Bulgarian]
OnlineВлезте в системата, за да прочетете пълната статия
First Ministry of Education Rules for Textbooks (1896)
B.V.T.Влезте в системата, за да прочетете пълната статия
John Dewey: How We Think (1910)
OnlineВлезте в системата, за да прочетете пълната статия