Laboratory instruction

Significant problems have been identified in the science education literature about the laboratory/practical courses, in particular about the ineffectiveness of laboratory instruction in enhancing conceptual understanding (Hofstein, 2004 Hofstein Lunetta, 1982 2004). The type of laboratory instruction plays certainly an important role in this deficiency. 

The most commonly applied style of laboratory instruction is the expositoiy one, which is instractor-centred. The learner has only to follow the teacher s instructions or the procedure (from the manual). The outcome is predetermined by the teacher and may also be already known to the learner. The results of the experiments... 

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. 

Domin, D. S. (1999b). A review of laboratory instruction styles. Journal of Chemical Education, 76, 543-547. 

Domin, D. S. (2007). Students perceptions of when conceptual development occurs during laboratory instruction. Chemistry Education Research and Practice, 8, 14-152. 

The revitalization of chemistry education has received much recent attention and taken many forms. Modes of teaching, textbooks, laboratory instruction— all aspects of the chemistry curriculum have undergone scrutiny for reform. A recent National Science Foundation report, Shaping the Future New Expectations for Undergraduate Education in Science, Mathematics, Engineering, and Technology characterizes the nature of the most successful curricular and pedagogical improvements ... 

As a conclusion to his preparative course the student should undertake several preparations, for which he has to look up the appropriate methods in scientific journals, instead of finding them worked out in minute detail in a manual of laboratory instruction. In so doing he will learn, with the aid of the directions given above, how to consult the literature, and how to make use of the chemical library most of all, however, these more difficult preparations will serve to test his capacity for laboratory work. When synthesising a compound in several stages it is absolutely essential to test and consolidate each separate stage by means of test-tube experiments before the whole of the substance is risked. Whoever fails to observe this rule will pay dearly for his neglect by loss of material and time. 

Domin (138) distinguished four types of laboratory instruction expository, inquiry, discovery, and problem-based. These styles can be differentiated by their outcome, their approach, and their procedure. Expository and problem-based activities typically follow a deductive approach, while inquiry and discovery activities are inductive. 

The same can be said for student high school laboratory experiences. While we may think our incoming college students have already mastered basic laboratory techniques in high school, that is often not the case. In fact, the National Research Council s (NRC) 2006 investigation of the state of laboratory instruction in high schools in the United States concluded the quality of current laboratory experiences is poor for most students (NRC 2006). In most high school laboratory pro-... 

Chemistry Laboratory Instruction and Research, Journal of Chemical Education, 66, pp. 77-84 (1989). 

Smeaton, W. A. The Early History of Laboratory Instruction in Chemistry at the Ecole Polytechnique, Paris, and Elsewhere. Annals of Science 10. 1954, 224-233. 

All potential points of leaks and other hot spots have to be identified in the stage of design. The decontamination procedures in case of accident have to be elaborated. The specification of the equipment for eventual decontamination and the means of decontamination are defined in laboratory instructions and manuals. All necessary safeguards and security systems are the elements of the project design. In case of emergency all means limiting the decontamination spreading out have to be used. 

With the adoption for the first time by the new United States Pharmacopceia of pharmacognic standards for numerous drugs. Pharmacognosy has risen to the forefront in this country as a science. While its proper comprehension requires laboratory instruction in chemistry, physics, and crystallography as well as botany, nevertheless a rather extended foundation in structural botany stands out preeminently as the most needed requirement. 

Absorption of dietary fat is a remarkably efficient process, so that in normal health, fecal fat is largely (if not entirely) derived from endogenous rather than dietary sources. Adequate dietary fat intake is therefore essential to minimize false-negative results. The BSG guidehnes recommend a diet containing at least 70 g fat for 6 days. In the UK only a minority of laboratories try to control (20%) or retrospectively assess (8%) fat intake. Patients with steatorrhea may reduce their fat intake to control their diarrhea and despite laboratory instructions may not increase their dietary fat... 

Such guidance can be given by (i) Laboratory instructions (ii) Laboratory manuals or (Hi) Instruction cards. 

Laboratory Instructions Laboratory instructions should be given in a clear and simple language. It should give a precise but systematic method of performing the experiment. Special emphasis be given on how the record is to be kept and number of observations to be taken. Calculations be clearly explained and precautions to be observed be specifically emphasised. 

Instruction Card In some laboratories instruction cards are used for providing guidance for laboratory work. Each student is given a card containing instructions about the experiment he has to perform. 

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