To illustrate the conception of d-TSpCk in operation, we draw on an exam- ple of teaching chemical equilibrium digitally. This example was extracted from an intervention for introducing d-TSpCk using chemical equilibrium in a methodology class of 4th-year pre-service chemistry teachers. The example illustrated here is from the teacher educator’s first video segment introduc- ing the topic by describing the pre-requisite conditions for the state of chem- ical equilibrium.
Example: A representative extract.
As noted before in the case of traditional TSpCk, not all activities in a teach- ing video are moments of d-TSpCk. However, there are specific moments when the interactions of traditional TSpCk are evidently digitally enabled.
This is to happen with considerations for a balance in the learner’s cogni- tive load when creating the digital content. The specific moments in this Figure 6.2 An illustrative model of d-TSpCk.
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specific teaching video were sequenced shots delivering the message about the pre-requisite conditions for chemical equilibrium.
The opening visual shot had a title introducing the topic of chemical equilib- rium as well as four hyperlinked statements that were about the Big Ideas of chem- ical equilibrium19 presented in chronological order as shown in Figure 6.3.
The hyperlinks led to teaching videos that were a composite part of the topic.
The educator clarified the segmented structure of the digital lessons as hyper- linked short videos to allow learner flexibility, differentiated learner prior knowl- edge and affording choice and control by the learner. This opening shot moved to the next uncluttered visual showing a symbolic representation of a chemically bal- anced equation for the forward reaction of sulfur dioxide (SO2 (g)) reacting with oxygen (O2 (g)) to form sulfur trioxide (SO3 (g)), using a single forward arrow. The educator explained what this chemical equation was representing, using her voice and displaying a passport size self-portrait in the bottom corner of the screen.
As she mentioned the single forward arrow and its meaning it was simultane- ously highlighted zooming out in size and changing in colour, see Figure 6.4. She then directed students to pay attention to the physical states of the reactants and products which dynamically zoomed out as she referred to each one. However,
Figure 6.3 illustrative interaction between segmenting and the Big ideas of the topic.
Figure 6.4 illustrative dynamic highlighting.
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77 A Framework for Learning to Teach Chemistry on a Digital Platform
no further explanation was provided at this point. She then introduced a static sub-microscopic representation of the reactants and products as solid spheres in distinguishable colours on the same plane, see Figure 6.5. These spheres entered a reaction vessel from each side, colliding to form products that were moving out of the container. She provided a description of this reaction pointing to the loss of products to the outside environment.
In the next shot she asked students to consider the same reaction happening in the reverse order, where the SO3 (g) was considered a reactant and the SO2 (g) and O2 (g) the resulting products. For this, she used a symbolic chemical equation also with a single forward arrow. She pointed out that if this reaction was happening in the same open vessel, it, too would go to completion and the products would be lost to the environment. The final scene was a visual animation of the same reac- tion using pre-counted sub-microscopic solid spheres to represent the reactants (SO2 and O2) in a closed container. She drew the attention of the students to the starting quantities of each reactant and asked them to pay attention to the reac- tion as it progressed. She used visuals of molecules of SO2 (g) and O2 (g) colliding and forming SO3, and the product breaking back into reactants. After some time has elapsed (a few seconds), she posed a question in form of a poll (using Edpuz- zle), asking students whether they think any of the reactions and their conditions if left undisturbed, would come to an end, and the reason for their answers. The Edpuzzle function enables students to access the correct explanation and proceed with the video on completion of their initial attempt. The correct answer was that neither reaction would come to an end, as the reactions are reversible in nature and occurring in a closed system.
Beyond the poll, the educator provided a summary of the most important con- tent to be learned in this video segment. The visual shot following the Edpuzzle task was a narrated representation of the three types of thermodynamic systems with arrows distinguishing each by the allowed exchange of either matter or/and energy or none. The representation of the closed system was linked to the earlier example of the reaction in a closed container discussed above. The same represen- tation was brought back and placed side by side with that of the closed system, see Figure 6.6. The educator highlighted the conditions of a closed system as enabling the reverse reaction to happen in the same container. She added that a non- Figure 6.5 illustrative use of multiple representations including sub-microscopic
representations.
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reversible reaction in nature will remain as such even in a closed system. Her verbal statement was synchronized with a view of a symbolic representation of the forward chemical reaction of SO2 (g) and O2 (g) and the reverse reaction of (SO3
(g)) placed on consecutive lines, each with single arrows still (without combin- ing them to use the chemical equilibrium double arrow yet). The final shots were visual examples of closed systems in the aqueous media.
in the above example, there are several transactions of multiple compo- nent interactions across traditional TSpCk and the pedagogical principles of multimedia digitally enabled. The design of the teaching reflects segmenta- tion into a set of short, interlinked teaching videos. The interlinked segments are purposely sequenced and given titles that reflect the core understanding to be mastered as the topic’s Big ideas. This reflects a transaction between the principle of multimedia called segmenting and the TSpCk’s curricular saliency providing an informed rationale in knowing what is core in a topic and considered necessary for learners to develop a comprehensive under- standing.19 There is evidence of appropriate choice and scaffolding of mean- ing through the use of multi-level representations including symbolic and sub-microscopic levels deemed essential for providing powerful in-depth explanations in chemistry.20 overlaying the use of multiple-level representa- tions is a repeated sense of curricular saliency emphasizing the most import- ant features in a representation. This is seen in the signposting for later discussion, the importance of noting the physical states of the reagents. Such emphasis is enabled digitally through the teacher’s competence in applying dynamic signaling. dynamic signaling is a powerful pedagogical multimedia principle for selectively placing appropriate cognitive load on important fea- tures for the learners’ attention. The sophistication of the transactions across the different constructs, ushers-in the emergence of the understanding of the pre-requisite conditions for chemical equilibrium. The teacher further Figure 6.6 An illustration of calculated omission for the use of the phrase ‘chem-
ical equilibrium’.
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79 A Framework for Learning to Teach Chemistry on a Digital Platform
blended to the observed transactions calculated omissions such as avoiding mentioning specific concepts such as ‘complete’ and ‘incomplete reactions’, preferring to use the term ‘coming into an end’. This is seen in the writing out of the forward and the reverse reactions separately beneath each other while avoiding combining the reactions yet. These omissions are informed by the recognition of the difficulty in understanding the notion of incomplete reac- tions before going into the next Big idea of dynamic equilibrium. it is also in calculating the timing for dealing with common learner misconceptions associated with thinking that reversible reactions go to completion at chem- ical equilibrium. Both these additional considerations are drawing from the components of the traditional TSpCk construct deepening the extent of the observed inter-construct transactions further. This example exhibits quite sophisticated interactive transactions across the three different theoretical constructs presented in Figure 6.2, with each construct bringing-in a dis- tinct characteristic effect. it illustrated the possible meaning of experiencing seamless transactions across teacher’s knowings and knows alive.