Schools Should Ask Students to Evaluate Their Teachers Essay Example

Schools Should Ask Students to Evaluate Their Teachers Essay Schools should ask students to evaluate their teachers. There are with no doubt a lot of good and experienced teachers, but in my opinion there are also a lot that do not belong in the classroom. Schools should ask students to evaluate their teachers in order to avoid choosing bad and inexperienced teachers, in order to learn what students like and dislike about the teaching methods and to make them feel more valuable for the school. First of all, a good teacher should have enough educational experience, he should know how to make himself understood, he should treat his students with respect, he should be helpful and concerned. A lot of teachers don’t have these qualities. If teachers are evaluated by their students and their opinions are really taken serious, I think that this problem would be if not entirely removed then at least reduced. Teachers play an important role in student’s lives and they should be very carefully chosen. Second of all, the quality of teaching is also very important and it is something that the administration of school cannot accurately estimate. Students should be able to grade and evaluate the teaching methods in class. They observe teachers’ work every day and can say what is easy or difficult for them, which activities they enjoy the most or what kind of exams they prefer. In addition to this, knowing that their opinions matter would make students feel more valuable for the school and less controlled by the teachers. We will write a custom essay sample on Schools Should Ask Students to Evaluate Their Teachers specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Schools Should Ask Students to Evaluate Their Teachers specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Schools Should Ask Students to Evaluate Their Teachers specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Students would feel better and more confident if they know that they are not the only ones that are going to be grated at the end of the year. Moreover, evaluating teachers is good for the students because is teaches them honesty and responsibility. To sum up, I think that evaluating teachers by students would be very useful for the whole educational system. It helps choosing the right teachers, the right teaching methods and it is beneficial for the students themselves.

Borons Chemical and Physical Properties

Boron's Chemical and Physical Properties Atomic number: 5Symbol: BAtomic weight: 10.811Electron configuration: [He]2s22p1Word origin: Arabic Buraq; Persian Burah. These are the Arabic and Persian words for borax.Isotopes: Natural boron is 19.78% boron-10 and 80.22% boron-11. B-10 and B-11 are the two stable isotopes of boron. Boron has a total of 11 known isotopes ranging from B-7 to B-17. Properties The melting point of boron is 2079Â °C, its boiling/sublimation point is at 2550Â °C, the specific gravity of crystalline boron is 2.34, the specific gravity of the amorphous form is 2.37, and its valence is 3. Boron has interesting optical properties. The boron mineral ulexite exhibits natural fiberoptic properties. Elemental boron transmits portions of infrared light. At room temperature, it is a poor electrical conductor, but it is a good conductor at high temperatures. Boron is capable of forming stable covalently bonded molecular networks. Boron filaments have high strength, yet are lightweight. The energy band gap of elemental boron is 1.50 to 1.56 eV, which is higher than that of silicon or germanium. Although elemental boron is not considered to be a poison, assimilation of boron compounds has a cumulative toxic effect. Uses Boron compounds are being evaluated for treating arthritis. Boron compounds are used to produce borosilicate glass. Boron nitride is extremely hard, behaves as an electrical insulator, yet conducts heat, and has lubricating properties similar to graphite. Amorphous boron provides a green color in pyrotechnic devices. Boron compounds, such as borax and boric acid, have many uses. Boron-10 is used as a control for nuclear reactors, to detect neutrons, and as a shield for nuclear radiation. Sources Boron is not found free in nature, although boron compounds have been known for thousands of years. Boron occurs as borates in borax and colemanite and as orthoboric acid in certain volcanic spring waters. The primary source of boron is the mineral rasorite, also called kernite, which is found in Californias Mojave Desert. Borax deposits are also found in Turkey. High-purity crystalline boron may be obtained by vapor phase reduction of boron trichloride or boron tribromide with hydrogen on electrically heated filaments. Boron trioxide may be heated with magnesium powder to obtain impure or amorphous boron, which is a brownish-black powder. Boron is available commercially at purities of 99.9999%. Quick Facts Element Classification: SemimetalDiscoverer: Sir H. Davy, J.L. Gay-Lussac, L.J. ThenardDiscovery date: 1808 (England/France)Density (g/cc): 2.34Appearance: Crystalline boron is hard, brittle, lustrous black semimetal. Amorphous boron is a brown powder.Boiling point: 4000 Â °CMelting point: 2075 Â °CAtomic radius (pm): 98Atomic volume (cc/mol): 4.6Covalent radius (pm): 82Ionic radius: 23 (3e)Specific heat (20Â °C J/g mol): 1.025Fusion heat (kJ/mol): 23.60Evaporation heat (kJ/mol): 504.5Debye temperature (K): 1250.00Pauling negativity number: 2.04First ionizing energy (kJ/mol): 800.2Oxidation states: 3Lattice structure: TetragonalLattice constant (Ã…): 8.730Lattice C/A ratio: 0.576CAS number: 7440-42-8 Trivia Boron has the highest boiling point of the semimetalsBoron has the highest melting point of the semimetalsBoron is added to glass to increase its resistance to heat shock. Most chemistry glassware is made from borosilicate glassThe isotope B-10 is a neutron absorber and used in control rods and emergency shutdown systems of nuclear generatorsThe countries Turkey and the United States have the largest reserves of boronBoron is used as a dopant in semiconductor production to make p-type semiconductorsBoron is a component of strong neodymium magnets (Nd2Fe14B magnets)Boron burns bright green in a flame test References Los Alamos National Laboratory (2001)Crescent Chemical Company (2001)Langes Handbook of Chemistry (1952)International Atomic Energy Agency ENSDF database (Oct 2010)

Essay Assignment Example | Topics and Well Written Essays - 1250 words

Essay - Assignment Example The decision by the New Plymouth District Council to bring to an end the water fluoridation is seen as thetermination of the practice in New Zealand. According to Mary Byrne of the anti-fluoride group, the Fluoride Action Network New Zealand, the New Plymouth District Council decision could bring a domino effect to other councils leading to the chemicals rejection (Stare, 1990). Fluoride, an ionic compound, contains the fluorine components. Fluoride, naturally found component in most of the rocks in New Zealand and worldwide, is the single most reactive element in water. Approximately 90 percent of the fluoride components added to the municipal water supplies come from the chemicals known as silicofluorides. The silicofluorides chemicals production is from the by-products of the manufacture of phosphate fertilizers. In most of New Zealand’s District Councils, fluoride is added to the municipal water supplies at the concentration of about one part per million or even slightly below. Fluoride concentrations occurring in surface waters depend on location, but concentrations are low, and in most cases do not exceed 0.3 ppm. Groundwater can however contain much higher concentration levels. Fluoride should not be included to the water supplied by district councils to the residents of cities and towns in New Zealand. A move by New Plymouth District Council is welcome and should act as a precedent to other district councils in New Zealand. Proponents of fluoridation argue that the fluoride helps by binding to tooth enamel. Enamel is primarily composed of hydroxylapatite; a crystal made up of phosphorus, calcium, oxygen and hydrogen. By replacement of hydroxyl molecule on hydroxylapatite, the resistance of the tooth to acidity attacks from bacteria will increase because of the fluoride components (Wagner, 1993). The proponents have however been