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Diagrams as models: Case of stomata

| Fri, Mar 22, 2024, 2:46 PM



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Diagrams are an integral part of doing and learning science. However, many students believe that the diagram they see in the textbooks are actual photographic representation of the real objects. They struggle to understand that diagrams are models like physical models of the solar system or atoms they may have seen in schools or outside. 

Partial reason why students have this misconception is because they never get to see real objects the diagram represents and we never show the process of creating diagrams by studying multiple examples of the specific objects (digram of cell or stomata).


In this post I suggest an activity to address the misconception and let students experience the process of construction of diagrams. I take stomata as an example.


Material required: Foldscope, transparent tape, fevicol or nailpolish, leaves of various plants (4-5), paper slide, pen and paper. 


Flow of activities:


1) Prior knowledge: through discussion the teacher/facilitator understands students prior knowledge about the stomata, their structure and function.

2) Activity 1 : Teacher/facilitator divides the classroom into the groups of 3-5 students, then shows the diagram of stomata given the textbook and asks to discuss how this diagram might have been created. Students discuss in their group discuss and write down their answers in a list of steps. One student from each group presents their answer and everyone listens.

3) Activity 2: Teacher/facilitator explains the activity, students work in previously formed groups. Task- students have to observe the stomatas of various leaves given to them by the teacher. Process of observing stomata: take a small drop of fevicol and apply a thin layer of it on the back side of the leaf. Let it dry. After it is dried in 1-2 minutes, take a small piece of tape 4-5 cm long and paste it above the layer of fevicol on the backside of the leaf. Then apply gentle pressure with your fingers to make sure that the tape is stuck to the layer of fevicol. Then peel the tape such that the layer of fevicol comes with it. Put the tape with the fevicol layer on a paper slide. Put the slide under the Foldscope and observe the stomatas. If students have phones they take photos, if not they draw what they see. The same protocol is repeated for each leave. After observing all the leaves students have to create a diagram of stomata such that it represents all the different stomatas they had observed. (for reference see the below photographs of stomata of different plants and diagram given in NCERT textbook)

4) Presentation and Discussion: All the group present their work. They show the diagram they created and talk about the process they followed. The teacher/facilitator uses the experience of activity to talk about how various diagrams they see in the textbooks are created. Specifically diagrams of various objects like cells, DNA, stomata, tissues, etc.

5) Future exploration: teacher/facilitator asks students to check all stomatas in terms of shapes, sizes, and numbers they can find around them.




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Categories

Type of Sample
information
Foldscope Lens Magnification
140x

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