LECTURE DEMONSTRATIONS

Bauer, C. F. Sampling Error Lecture Demonstration, /. Chem. Educ. 1985, 62, 253. 

Symposium on Lecture Demonstrations, 115th Meeting, Am. Chem. Soc., San Francisco, Calif., 1949. 

Of particular relevance to the above discussion is the way in which learners initially handle incoming iuformation such as that presented in a lesson, a lecture demonstration or during laboratory instruction. The new irrformation is perceived and filtered in terms of what the learner already knows and canimderstand. As a result, iuformation is not transferred intact from the mind of the teacher to the mind of the learner. It undergoes an initial selection (filtration) process and what is admitted will vary from person to person. Students with a similar backgrottrrd will tend to select in a similar, but not identical, way (Johnstone, 2007). An information-processing model is presented in Fig. 5.1. 

Despite the fact that the students do not consider lecture demonstrations as effective as active performance of experiments as discussed previously, there is often the case that during experimental work vital observations are obscured by powerful, but less important stimuli. In such cases, demonstrations, rather than individual laboratoiy work, may be the best procedure. In a demonstration, the teacher has control and can focus attention on the salient observations (Johnstone Shuaili, 2001) and demonstrations can also form the basis for providing a broader technique for assessment of learning (Bowen Phelps, 1997). 

According to Ashkenazi and Weaver (2007), lecture demonstrations can provide essential experiences that serve as a context for discussion of over-generalized or over-simplified concepts. The design of such demonstrations starts from surveying... 

It is expected that, in the future, inquiry, project-, problem- and context-based approaches will be given more emphasis. Cooperative forms of laboratory instmc-tion must surely be further and systematically explored, taking into account the research-based recormnendations. Lecture demonstrations, effectively designed and performed, will also be useful. Other nonconventional methods can be effectively employed, such as the use of home-laboratory kits to teach general chemistry through distance education (Kermepohl, 2007). 

Ashkenazi, G., Weaver, G. C. (2007). Using lecture demonstrations to promote the refinement of concepts The case of teaching solvent miscibility. Chemistry Education Research andPractice, 8, 186-196. 

Bodner, G. M. (2001). Why lecture demonstrations are exocharmic for both students and their instructors. University Chemistry Education, 5, 31-35. 

Sodium nitromethanoate is relatively stable when solvated. The dry salt is a sensitive and powerful explosive which may be detonated by warming to 100°C, by a strong blow or contact with traces of water. The potassium salt is even more sensitive. Lecture demonstrations of these properties are described. 

Accidental contamination of a metal scoop with flake sodium hydroxide, prior to its use with zinc dust, caused ignition of the latter [1]. A stiff paste prepared from zinc dust and 10% sodium hydroxide solution attains a temperature above 100°C after exposure to air for 15 min [2], The residue of zinc dust and sodium hydroxide solution from a lecture demonstration involving zinc plating a copper coin presents a high fire risk if discarded onto paper in a waste bin, ignition of the paper having occurred on many occasions. Dissolve the residue in dilute acid before flushing away with water [3],... 

A variety of chemical lecture demonstrations involving unstable or highly reactive materials which have led to accidents are reviewed, and practical suggestions made to avoid such incidents [1]. Safety aspects are discussed and some relevant books and articles reviewed [2],... 

Sampling error lecture demonstrations have been published by Bauer and Kratochvil 15-1 . A software program allowing simulation of many sampling situations and providing calculation algorithms for sampling schemes has been published... 

An interesting lecture demonstration is the Vesuvius experiment, in which a small mound of (NH4)2Cr207 is heated to commence decomposition It then continues its decomposition unaided, gives off heat light and sparks, and leaves a mountain of Cr203 he reaction is... 

I he first recorded observation of cool flames was made by Davy (15), Perkin (33) further explored the phenomenon, developing what might be described as a lecture demonstration technique and noting that aldehydes and acids were produced. Leighton (21), at the suggestion of W. D. Bancroft, reinvestigated and confirmed Perkin s observations. 

Azidodithiocarbonic acid, azidocarbondisulfide, and the azidodithiocarbonates are useful substances in illustrating the properties of halogenoids. Rather spectacular lecture demonstrations may be made by using these compounds, but they should not be attempted except by an experienced chemist. Some of the heavy metal azidodithiocarbonates are powerful detonators but have proved too sensitive for practical application. 

Lanthanide iodide silicides, 200 Lanthanide metals, 200 Lanthanide nitrobenzoates, 200 Lanthanide—transition metal alloy hydrides, 201 Lassaigne test, 201 Lead salts of nitro compounds, 201 Lecture demonstrations, 202 Light alloys, 202 Lime fusion, 202 Linseed oil, 202 Liquefied gases, 203 Liquefied natural gas, 203 Liquefied petroleum gases, 203 Liquid air, 204 Liquid nitrogen cooling, 205 Lithium peralkyluranates, 205 Lubricants, 205 Lycopodium powder, 205... 

The third International Dendrimer Symposium took place at Berlin Technical University in 2003. Interdisciplinary lectures demonstrated the extent to which dendritic molecules branch ouf into other areas of science, such as physics, biology, medicine, and engineering. The possibilities of functionalisation and resulting applications in industry were at the focus of this symposium. For example, nano-dimensioned dendrimer-based contrast agents were presented as multilabels for visualisation of blood vessels (see Chapter 8). Potential applications of dendritic materials as luminescence markers in diagnostics attracted lively interest (see Chapter 8). Consideration of the differences between dendrimers and hyperbranched polymers from the viewpoint of their cost-favourable application was also a topic of discussion [18]. 

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