Macro tasking

Some tasks in the Test of Gained Knowledge required students to connect observations about the macro course of chemical reactions with their notations in the submicro and/or symbolic types of representation. The results indicate that most students were able to rearticulate the information about reactants and products of a chemical reaction from the textual description of chemical reaction into the form of word chemical equation (textual description of macros word equation of macro Task 8.2, f(o/ )=89.82% Task 9.1, f(o/ )=87.61%). This action corresponds to the first step in learning to write down chemical equation in the LON approach. It can easily be explained, because teachers described the learning process to be very efficient to this point, as is illustrated below ... 

There are several things that can be noticed in this arrangement. Firstly, the attributes of the objects influence the attributes of actions secondly, the Add and the Pour actions have motion and equipment requirements. The profile of motion is dictated by the attributes of sugar and within this profile is inherent the quality of the task and also the time involved to perform it. The description Add Sugar is a macro task, whilst the action profile is a micro task and the sequence of events ensure the precedence. This provides the mechanism to structure and visualise process information as shown below ... 

Figure 3. The XSophe (v 1.1.4) main Window. The interface allows creation and execution of multiple input files on local or remote hosts. There are macro task buttons to guide the novice through the various menus and two button bars to allow easy access to the menus. For example, the bottom bar (left to right), Experimental Parameters, Spin System, Spin Hamiltonian, Instrumental Parameters, Single Crystal Settings, Lineshape Parameters, Transition Labels/Probabilities, File Parameters, Sophe Grid Parameters, Optimisation Parameters, Execution Parameters and Batch Parameters.

The first phase is a clear definition of the scope of work that is to be performed during the shutdown or maintenance outage. This definition must be more than a macro-level listing of the major tasks that are to be performed. Instead, each of these major or macro-level tasks must be fully defined. The purpose of this procedure is to provide an effective method of planning, material control, and follow-up of repetitive, non-repetitive, and capital shutdown work. 

Owing to the laborious task of obtaining corrosion rates from gravimetric measurements, data for the effect of exposure time on corrosion rates have been very limited. However, with the more recent use of polarisation resistance measurements it would appear that in the absence of macro-biofouling... 

Meijer, M. R., Bulte, A. M. W., Pilof A. (in this book). Stmcture-property relations between macro and micro representations Relevant meso-levels in authentic tasks. In John K. Gilbert David F. Treagust (Eds.), Multiple representations in chemical education, pp. 195-214. 

Structure-Property Relations Between Macro and Micro Representations Relevant Meso-levels in Authentic Tasks... 

The content of a curriculum must be functional when dealing with societal activities necessary chemical concepts, skills and attitudes with respect to macro-micro thinking must be included. This can be derived from representative authentic tasks. The content of the curriculum should be considered as a chemical toolbox. The traditional content of the present chemistry curriculum, such as the stmcture of atoms, ionic theoiy, fundamental acid-base calculations, are not necessarily part of the chemical toolbox when addressing chemical and technological tasks. The validity of the toolbox (philosophical substmcture) is determined by the representative practices and tasks related to chemistry (cf need-to-know principle in context-based approaches). 

With respect to the nature of the tasks, we chose a developmental or a design task because we expected that such a behavioural environment (Gilbert, 2006) is closer to the lives of students. Besides, these tasks may offer opportimities for experimentation and hands-on activities in classrooms, when such tasks are meant as contexts for learning macro-micro thinking. 

To summarise in authentic tasks, we have established that stmcture-property relations can be described by a dynamic system of stmctures, properties and their interrelations. Within the limits of our study we have derived a generalised conceptual schema, which we expect to be useful to teach macro-micro problems in which stmcture-property relations can be explicitly used (Figs. 9.2, 9.3 and 9.4). The system of nested stmctures, systematically assigned to appropriate scales, and the properties of the different stmctural components reveal a conceptual schema necessary for macro-micro thinking. The system of relevant nested stmctures and the explicit relations between stmctures and properties form the backbone of macro-micro reasoning. Depending on the task, a number of different meso-levels are relevant and... 

Fig. 9.3 The conceptual schema of micro-macro thinking for the task designing gluten-free com bread, with the explicit use of structure-property relations...

This section began with a class discussion about the importance of water softening and the different factors that influence water hardness. As an example of everyday situation, the efficiency of dishwasher Finish salt was presented. A set of short chemical experiments entitled Testing the dishwasher Finish salt was carried out as a wet laboratory task in groups of students (macro). Later on teachers explained one of those chemical experiments by the use of an animation and also by its 2D presentation with models then students in groups tried to write 2D representations for other chemical experiments (submicro). Students also tried to write down word and symbolic equations and to select the appropriate energy diagrams (symbolic). The results of students work were discussed and corrected when necessary. 

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