Teaching Chemistry with Analogies: Mapping Types of Bond Fission with Divorce Cases

Introduction

I want to appreciate you all for the time taken to read and comment on my previous post on 'exploit your learning style'. It was very encouraging. In this post, I would like to share from my teaching experience, an effective tool for teaching Science concepts.

I was teaching the concept of Bond fission in covalent bonds to a group of students sometimes ago. As much as I tried breaking down the topic into simple terms, I looked at their faces and I knew I hadn’t scored a goal point in their assimilation goal post (I live with football freaks). I then planned using analogies being one of the instructional strategies I worked on for my thesis.

Analogies in teaching process

Analogy could be explained as the mapping between similar features of familiar concrete knowledge in the world of the learner(Analog) and the unfamiliar, abstract topics, concepts, principles or formulas (target domain). Analogies work on students’ imagination and give students opportunity to relate features and functions of daily life objects or events to similar features of an abstract science topic or concept. The analog and target domain must share attributes that allow for a relationship to be easily identified.

Analogies could do as much harm as good if not handled appropriately. The learners must be able to identify the similarities between analog and target domain and be able to transfer these attribute to the target domain without misconception. In other to curtail these constraints, teachers should know the prior knowledge of the learners from which to pick the relevant analog. The features of analog and target domain should be clearly mapped out for easy clarification of the existing relationship.
Analogies could be Physical (involving concrete, physical objects being manipulated) or Verbal (description of an event or a phenomenon). The use of analogy in enhancing the teaching process has been known to:

• provide visualization of abstract,
• provide a link between abstract and real world of the learners, and
• provide motivational function.

The use of analogy could be on the spur of the moment or pre-planned as the case may be. After I perceived that the students did not really understand the concept, I then pre-planned a verbal analogy (like telling a story) for the next lesson. The analogy involved a fictional description of three divorce cases to teach the concept of bond fission in covalent bonds.

Case 1

The first case I presented to them was of the marriage between a man and woman from similar socio-economic background and both at the same income level. Initially when they were about tying the knot, they both brought the same value of asset into the marriage. Now that they want to break up, there is no laid down constitution, the division of the assets depends on how powerful each spouse is. Since they have similar socio-economic background and no external interference, the assets were divided equally between the two parties. They became financially independent and free.

Pixabay CCO Licensed

Case 2

This is about the divorce rule of the marriage between a man and woman from similar socio-economic background with same income level. Both contributed equally to the asset value of the marriage. However, there is a twist here, one party has a friend with connections in the corridor of power and this friend is interested in the break up and especially has eyes feasted on the property division involved. The asset was divided unequally between them even though they are from similar socio-economic background. The presence of the friend with external influence tipped the division of asset to favor the spouse with the powerful friend making the spouse extra rich, while the other becomes financially drained.

Pixabay CCO Licensed

Case 3

This divorce rule involves the marriage between a man and a woman from different socio-economic background. Though they contributed equally to the asset value of the marriage, one spouse is from a very rich home while the other is from poor background. The one from a rich home wants to be richer and therefore influenced the division of asset. The asset was divided unequally between them to favor the richer spouse to become extra rich, while the other becomes financially drained, even though they contributed equally to the asset value of the marriage.

Analogical relationship: Mapping of the Analog to the Target domain)

Analog………………………………................................................Target domain
Equal sharing of asset value of marriage……………………Homolytic fission (Equal sharing of bond electrons)
Similar socio-economic background……………………… similar electronegativity
Same contribution to marriage………………………………equal electron donation to bond shared
Marriage……………………………………………………… covalent bonding
Divorce………………………………………………………… bond fission
Financially independent and free……………………………free radicals
Man and a woman…………………………………………… two atoms bonding
Asset value…………………………………………………… bond electrons
Friend with higher connection…………………initiator catalyst (e.g. Friedel Craft’s catalyst in halogen fission)
Different socio economic background…………………........different electronegativity
Richer spouse………………………………………………….more electronegative atom
Unequal sharing of asset value……………… Heterolytic fission (unequal sharing of bond electrons)
Extra rich……………………………………………………… .Nucleophile (electron rich specie)
Financially drained……………………………………………Electrophile (electron deficient specie)

Analogical reasoning/correlation

Case 1
Homoltytic fission is a type of bond fission that occurs between two atoms of similar electronegativity bonded together in a covalent bond. The bond breaks with equal sharing of the bond electrons to give free radicals each with the electron donated during the covalent bonding.

Jordan Levine CCO 4.0

Case 2
When two atoms of the same electronegativity share a covalent bond, if there is an external influence like in the case of halogen molecules, in the presence of AlCl3( Friedel Craft’s catalyst), the bond will break unequally to favor one of the halogen atoms which would be picked up by the Friedel-craft’s catalyst. The bond fission will therefore be a heterolytic fission. In which the bond electrons move to the atom attached to the external factor and it becomes electron rich (Nucleophile). Leaving the other atom as electron deficient (Electrophile).

Case 3
When two atoms of different electronegativity are in covalent bonding, the bond fission would involve the more electronegative atom drawing the bond electrons towards itself, thereby becoming electron rich( Nucleophile), while the other becomes electron deficient ( Electrophile).

Jurgen Martens CCO 3.0

Conclusion

I discovered that throughout the period of instruction, I had the attention of the students and their faces were lit up with interest. I made sure there was no misconception in the transfer of attributes of the analogue to the target domain by repeatedly referring to the pictorial mapping I made above. At the end of the class, the feedback I got from the students in form of verbal answers to questions asked on the concepts taught was very encouraging.
I believe if lecturers, teachers and other instructors in the field of science could use analogies to enhance the teaching of certain topics which they perceive to be abstract or difficult to understand by the students, the attitude, interest and ultimately the performance of students in science courses would take a positive turn. Moreover, students would be motivated into expanding their imagination and the ability to convert abstract knowledge into concrete understanding in relation to everyday living.
Thanks for taking time out to read this post.

References

1. https://onlinelibrary.wiley.com/doi/pdf/10.1002/sce.3730640516
2. http://acikerisim.deu.edu.tr/xmlui/bitstream/handle/12345/5213/525-534.pdf?sequence=1&isAllowed=y
3. https://files.eric.ed.gov/fulltext/EJ1086234.pdf
4. https://files.eric.ed.gov/fulltext/EJ1095360.pdf
5. http://uakron.edu/cpspe/agpa-k12outreach/best-teaching-practices/using-analogies
6. https://pdfs.semanticscholar.org/9fe1/739734727058038444305105c7af5326de39.pdf