Spectroscopy for primary school teachers?

Will Raman spectroscopy provide future primary teachers with "a dynamic and attractive vision of science, technology and innovation"?

Keith S. Taber

…a proposal of methodology for the subject of experimental sciences for teachers in training, which will introduce real scientific instrumentation such as Raman spectroscopy, which can be of great interest to perform significant learning and to design teaching-learning activities

Morillas & Etxabe-Urbieta, 2020, p.17

I am going to offer a critical take on a proposal to teach future primary teachers to use Raman spectroscopy. That is, a proposal published in a leading international research journal (well, that is how the journal describes itself).

I do have some reservations about doing this: it is very easy to find fault in others' work (and a cynic might suggest that being an academic is basically a perpetual ongoing training in that skill). And there are features of the proposal that are appealing.

For a start, I like spectroscopy. I sometimes joke that my first degree was in spectroscopy and some of its applications (although the degree certificate refers to this as chemistry). I also like the way the paper refers to principles of models of learning, and refers to "combining concepts of chemistry and physics" (Morillas & Etxabe-Urbieta, 2020: 17).

However, I do wonder how closely (and critically) the editor and peer reviewers (assuming there really was peer review) actually read the submitted manuscript – given the range of questions one would expect to have arisen in review.

I will, below, question whether this contribution, a proposed teaching scheme, should really be considered a 'research' article. Even if one thinks it should be, I suggest the authors could have been better supported by the journal in getting their work ready for publication.

A predatory journal

I have been reading some papers in a journal that I believed, on the basis of its misleading title and website details, was an example of a poor-quality predatory journal. That is, a journal which encourages submissions simply to be able to charge a publication fee (currently $1519, according to the website), without doing the proper job of editorial scrutiny. I wanted to test this initial evaluation by looking at the quality of some of the work published.

Although the journal is called the Journal of Chemistry: Education Research and Practice (not to be confused, even if the publishers would like it to be, with the well-established journal Chemistry Education Research and Practice) only a few of the papers published are actually education studies. One of the articles that IS on an educational topic is called 'Raman Spectroscopy: A Proposal for Didactic Innovation (IKD Model) In the Experimental Science Subject of the 3rd Year of the Primary Education Degree' (Morillas & Etxabe-Urbieta, 2020).

Like other work I have examined in this journal, the published article raises issues and questions which one would imagine should have arisen during peer review – that is when expert evaluators look to see if a manuscript has the importance and quality to be worthy of journal publication.

Below I very briefly outline the nature of the proposed innovation, and then offer some critique.

A proposal for didactic innovation in the primary education degree

Morillas and Etxabe-Urbieta (i) propose a sequence of practical science work for inclusion in the curriculum of undergraduate students who are preparing for primary school teaching, (ii) link this, in broad terms at least, to pedagogic principles, and (iii) make claims about the benefits of the mooted proposal.

The authors consider their proposal has originality, as they could not find other literature recommending the use of Raman spectroscopy in the preparation of primary school teachers,

"…the fact that there are no works related to Raman spectroscopy to work on concepts developed in experimental science class for Teacher training in Primary Education in formation, makes the proposal that is presented more important."

Morillas & Etxabe-Urbieta, 2020: 17

What exactly is proposed?

Morillas and Etxabe-Urbieta suggest an extended sequence of laboratory work with three main stages:

• students are provided with three compounds (sodium nitrate; potassium nitrate; ammonium dihydrogen phosphate) from which they will prepare saturated solutions, from which crystals will grow ;
• the resulting crystals will be inspected, and examples of crystals with clear shapes will be selected and analysed in terms of their geometries – showing how different compounds lead to different crystal structures
• examples of ill-formed crystals will be subjected to Raman spectroscopy, where the three different compounds will give rise to different 'fingerprints'.

Pedagogic theory

Morillas and Etxabe-Urbieta report that their work is based on the 'IKD model' which equates to "new innovative teaching methodologies":

"In recent years, new innovative teaching methodologies have been used in the Basque Country University (IKD model) for experimental science classes for teachers of Primary Education in formation. This IKD model is based on a cooperative and dynamic learning. It is an own [?], cooperative, multilingual and inclusive model that emphasizes that students are the owners of their learning and are formed in a comprehensive, flexible and adapted to the needs of society. Training students according to IKD model requires creating new ways of teaching and learning more active and cooperative (curriculum development). Therefore, the fact of combining more theoretical master classes with more practical classes is a trend that is increasingly used."

Morillas & Etxabe-Urbieta, 2020: abstract

The authors name check constructivism, meaningful learning, and the notion of learning cycles, without offering much detail of what they mean by these terms.

"The students can put into practice the solubility concepts in master classes, through activities based on the IKD didactic model of the University of the Basque Country and in constructivist models of teaching and learning. Learning cycles have been developed and in a group, dynamic and cooperative way, the students explore their previous knowledge about solubility and crystallization, reflect on these ideas, make meaningful learning and apply these new learning in research contexts in the laboratory. In particular it has been discussed in the classroom about the amount of salt (compound) that can be dissolved in water and has been investigated on the factors that influence the solubility and on the crystallization process."

Morillas & Etxabe-Urbieta, 2020: 18

There is very little detail of how these pedagogic principles are built upon in the proposed teaching scheme, and the 'IKD model' is not explained in any more detail (e.g., how does 'multilingual' learning fit with this proposal?) After all, school children have been making saturated solutions and growing crystals for generations without this being understood as part of some innovative educational practice.

What is claimed?

Overall, the sequence is said to help link scientific theory to practice, teach geological concepts and provide hands-on experience of using modern scientific instruments,

"the first part, where the crystallization of various chemical compounds is carried out, will help to pinpoint possible doubts arising in the master classes of the chemistry part. Next, it is analyzed how to differentiate the crystals by means of their type of geometry in its crystallization based on geological concepts. Finally, the crystals are differentiated by another method based on the Raman spectroscopy…where students can observe concepts of light treated in physics class such as lasers, and electromagnetic lengths [sic?], where for the case in which some crystals that are not perfectly crystallized, this portable equipment will be used. In this way, the students have their first experience of this type, and use real scientific instrumentation."

Morillas & Etxabe-Urbieta, 2020: 18

Stage one: preparing crystals

But the authors suggest the approach has further impacts. Dissolving the salts, and then observing the crystals grow, "can help the student

• to encourage possible scientific vocations,
• better understanding of theoretical master classes and
• letting them know how is [what it is like?] working in the scientific field and
• spreading the importance of crystallography in our society" (p.18)

So, in addition to linking to theory classes ("students will begin to use the laboratory material studied in the theoretical classes, using and observing its characteristics, and in the same way trying to correlate the concepts of chemical saturation previously learnt in master classes", p.18), this simple practical work, is expected to change student views about science careers, give authentic experience of doing science, and increase social awareness of crystallography as a scientific field. Perhaps, but this seems a lot to expect from what is a pretty standard school practical activity.

However, in case we are not convinced, the authors reinforce their claims: students will experience principles they have been taught about saturated solutions, and how solubility [often] changes with temperature, and

"the students begin to experience the first fundamental concepts of crystallography and subsequently the fact of observing week after week the growth of the crystals themselves, can help the student to encourage possible scientific vocations, better understanding of theoretical master classes and letting them know how is working in the scientific field and spreading the importance of crystallography in our society."

Morillas & Etxabe-Urbieta, 2020: 19

Some of this is perfectly reasonable, but some of these claims seem speculative. (Simply repeating an unsupported claim again on the following page does not make it more convincing.) Authentic scientific activity would surely involve extended engagement, developing and testing a procedure over time to hone a process – crystallising solutions does not become an authentic science activity simply because the evaporation takes place over several weeks.

An editor or peer reviewer might reasonably ask "how do you know this activity will have these effects?"

Stage 2: Characterising crystals

In the second stage, students examine the three types of crystals formed and notice and document that they have different shapes/geometries. This requires careful observation, and measurement (of angles),

In a second phase, once that month passed, the students will observe the crystals that have grown inside their containers. Firstly, one of the objectives will be to observe what kind of crystals have formed. For the observation methodology and subsequent for the description of them, teacher will give some guidelines to distinguish the formed crystals according to their geometry based on the geological morphology.

Morillas & Etxabe-Urbieta, 2020: 19

Growing and examining crystals seems a worthwhile topic in primary school as it can encourage awe and wonder in nature, and close observation of natural phenomena: the kinds of activities one might employ to engage young minds with the world of science (Taber, 2019). The authors expect (undergraduate) students to recognise the different crystal systems ("trigonal … orthorombic … tetragonal") and associated angles between faces. ¹ This phase of the work is reasonably said to be able to

• "promote skills such as visual and spatial perception"

It is the third stage of the work which seems to go beyond the scope of traditional work in preparing primary school teachers.

Stage 3: Using Raman spectroscopy to (i) identify compounds / (ii) appreciate particle movements

In this stage, groups of students are given samples of each of the compounds (from any of the students' specimens that did not crystallise well enough to be identified from the crystal shape), and they obtain Raman spectra from the samples, and so identify them based on being informed that the main spectral peak falls at a different wavenumber for each salt.

An inauthentic activity?

There is a sense that this rather falls down as an inquiry activity, as the students knew what the samples were, because they made the solutions and set up the crystallisations – and so presumably labelled their specimens as would be usual good scientific practice. The only reason they may now need to identity samples is because the teaching staff have deliberately mixed them up. Most school practical work is artificial in that sense, but it seems a little forced as an excuse to use spectroscopy. A flame test would surely have done the job more readily?

A black box

Now the way the procedure is explained in the article, the spectrometer works as a black box that leads to spectra that (if all has gone well) have characteristics peaks at 1067 cm^-1, 1048 cm^-1 or 921 cm^-1 allowing the samples to be distinguished. After all, a forensics expert does not have to understand how and why we all form unique fingerprints to be able to compare fingerprints found at a crime scene with those taken from suspects. (They simply need to know that fingerprints vary between people, and have skills in making valid matches.)

Yet Morillas and Etxabe-Urbieta (p.21) claim more: that undertaking this third part of the sequence will enable students to

• "relate the type of movements that occur in the materials particles, in this case crystals, where the concept of particles movement…
• the fact of lasers use in a realistic way helps also students to understand how these kinds of concepts exist in the reality and are not science fiction
• …the use of this type of instrumentation in television series such as CSI, for example, means that students pay more attention in classrooms
• and help them to grow a basic scientific curiosity in their professional work, that is, in the Primary Education classrooms"

Again, perhaps, but where is the evidence for this? If one wanted to persuade future teachers that lasers are not just science fiction, one could refer to a laser pointer, or a CD, DVD or Blu-ray player.

Final claims

The authors end their proposal with some final claims

"The methodology proposal presented in this work, based on IKD model explained [sic, I do not think it was – at least not in any detailed way] above, will offer to Primary Education degree students a great possibility of applicability as a teaching resource, in which the fact of using Raman spectroscopy as a real scientific instrumentation can fill them with curiosity, amazement and interest. Moreover, this technique cannot only be used as a complement to this type of work [?], but also for didactic innovation projects and research projects. Thus, the fact of being able to use this type of tools means that the students are stimulated by their curiosity and desire to advance and learn, progressing in their scientific concern and therefore, improving the delivery of their future classes in a more motivated, didactic and rigorous way."

Morillas & Etxabe-Urbieta, 2020: 21

A devil's advocate might counter that an activity to identify poorly crystallised salts by subjecting them to a black box apparatus that produces messy graphs which are interrogated in terms of some mysterious catalogue of spectral lines will do very little to encourage "curiosity, amazement and interest" among any future primary school teachers who already lack confidence and enthusiasm for science. Indeed, without a good understanding of a range of underlying physical principles, the activity can offer about as much insight into science as predicting the outcome of a football match from a guide to interpreting tea leaves.

So, perhaps less like identifying fingerprints, and more like reading palms.

• 

• 

The references to "offer to Primary Education degree students a great possibility of applicability as a teaching resource" and "improving the delivery of their future classes in a more motivated, didactic and rigorous way" seems to mean ¹ that the authors are not just suggesting that the undergraduates might benefit from this as learners, but also that they may want to introduce Raman spectroscopy into their own future teaching in primary schools.

That seems ambitious.

Spectroscopy in the school curriculum

Spectroscopy does appear in the upper levels of the secondary school curriculum, but not usually Raman spectroscopy.

Arguably, mass spectrometry ² is most accessible as a general idea as it can be explained in terms of basic physical principles that are emphasised in school physics – mass, charge, force, acceleration… 'Mass spec.' – the chemist's elemental analyser – also offers a nice context for talking about the evidence for the existence of elements with distinct atomic numbers, and for looking at isotopic composition, as well as distinguishing elements and compounds, and testing for chemical changes (Taber, 2012).

'Mass spec.' is, however, rather different to the other main types of spectroscopy in which samples are subjected to electromagnetic radiation and the outcome of any interaction detected. ²

Most spectroscopy involves firing a beam of radiation at a sample, shifting gradually through a frequency range, to see which frequencies are absorbed or re-emitted. Visible spectroscopy is perhaps the most accessible form as the principle can initially be introduced with simple hand-held spectroscopes that can be used to examine different visible light sources – rather than having to interpret chart recorder or computer screen graphics. Once students are familiar with these spectroscopes, more sophisticated spectrometers can be introduced. UV-Visible (UV-Vis) spectroscopy can be related to teaching about electronic energy levels, for example in simple models of atomic structure.

Infrared (IR) spectroscopy has similar principles, and can be related to the vibrations in molecules due to the presence of different bonds. Vibrational energy levels tend to be much closer together than discrete ³ electronic levels

In these types of spectroscopy, some broad ranges of frequencies of radiation are largely unaffected by the test sample but within these bands are narrow ranges of radiation that are being absorbed to a considerable extent. These 'spectral peaks' of frequencies* of the radiation being removed (or heavily attenuated) from the spectrum reflect energy transitions due to electrons or bonds being excited to higher energy levels. (Although energy absorbed will often then be re-emitted, it will be emitted in arbitrary directions so very little will end up aligned with the detector.)

[* Traditionally in spectroscopy the peaks are labelled not with radiation frequency by with wavenumber in cm^-1 (waves per cm). This is the reciprocal of wavelength, λ, (in cm), and so directly proportional to frequency, as speed of the radiation c = fλ.]

A more subtle kind of spectrocsopy

Raman spectroscopy is inherently more complex, and relies on interactions between the material under test and a very small proportion of the incident radiation. Raman spectroscopy relies on a scattering effect, so as a simple analogy it is like UV/Visible or IR spectroscopy but involving something more like a Doppler shift than simple absorption. Thus the need for a monochromatic light source (the laser) as the detector is seeking shifts from the original frequency.

So, if introducing spectroscopy one would be better advised to start with UV-Vis (or IR) where there is a strong contrast in absorption between unaffected and affected frequencies, and where there is a direct relationship between the energy of the affected radiation and the energy transitions being indirectly detected (rather than Raman spectroscopy where there is only a marginal difference between affected and unaffected frequencies, and the scattered radiation does not directly give the frequencies of the energy shifts being indirectly detected).

Learning quanta – teaching through an Aufbau principle

As learning tends to be an incremental process, building on existing knowledge, it would probably make sense to

• introduce spectroscopy in terms of UV-Vis, first with hand held spectroscopes, then spectrometers
• then extend this to IR which is similar in terms of basic principles and so would reinforce that learning.

Only later, once this basic understanding had been sufficiently revisited and consolidated, would it seem to make sense to

• move onto the more complex nature of Raman spectroscopy (or nuclear magnetic resonance spectroscopy which involves similar complications).

This, at least, would seem to be a constructivist approach – which would align with Morillas and Etxabe-Urbieta's claim of employing "Teaching and Learning processes based on Constructivism theories and IKD model of the Basque Country University" (p.18).

That is, of course, if it is felt important enough to teach primary school teachers about spectroscopy.

…and as if by magic…

Actually, I am not at all convinced that

"thanks to the visualization of these spectra, students can relate the type of movements that occur in the materials particles, in this case crystals, where the concept of particles movement, which is quite abstract, can be understood"

The future teachers could certainly be taught that

"this type of technique consists in that the laser of the equipment (in our case red laser) when striking on the crystals promotes an excitation of the molecules [sic, ions?] of the own crystal, that can vibrate, rotate [sic ⁴] etc. This type of excitation is translated into a spectrum (different peaks) that is displayed on the screen of a computer connected to the Raman spectrometer. These peaks refer to different vibrational modes of the molecules [sic], so that each of the bands of each spectrum, corresponds to different parts of the molecule [sic], so as it has been mentioned above, each of the crystals has its own fingerprint"

Morillas & Etxabe-Urbieta, 2020: 20

Yet that seems some way short of actually relating the spectra to the "type of movements that occur in the materials particles". (In terms of my fingerprint analogy, this is like being taught that the unique fingerprint reflects the epigenetic development of the individual, and so appreciating why different people have different fingerprints, but still not being able to relate the specific fingerprints of individual to any specific events in their development.)

Not a research paper – or even a practice paper?

I do not think this article would been publishable in a serious research journal, as it does not seem to report any actual research. It discusses educational practice, but it is not clear if this is practice that currently takes place or is simply being proposed. Even if this is reporting actual teaching practice, there is no evaluation of that practice.

The idea that Raman spectroscopy might be beneficial to future primary school teachers seems somewhat speculative. I have no doubt it could potentially be of some value. All other things being equal, the more science that primary school teachers know, understand, and are confident about, the better for them and their future pupils.

But of course, all other things are seldom equal. In general, teaching something new means less time for something else. Either Raman spectroscopy replaces something, or it squeezes the time available, and therefore the engagement and depth of treatment possible, in some other curriculum content.

So, rather than making great claims about how including Raman spectroscopy in the curriculum will help learn theory (will they really understand how a laser produces coherent monochromatic light, and how and why scattering takes place?), provide experience of scientific work (with an artificial exercise?), lead to scientific vocations (instead of becoming primary teachers?), and raise social awareness of crystallography, etc., what is needed is evidence that some of these educational aims and objectives are being met. And, ideally, that there is more educational gain with this activity than whatever it replaced.

I am certainly not looking to reject this proposal out of hand. I can see the sequence could engage students and be enjoyable, and may well have positive outcomes. But simply making a range of unsubstantiated claims is not research. A speculative proposal offering tenuous arguments for knowledge claims is not sufficient for a research paper.

Evaluating these claims would not be that easy (some of the effects claimed are pretty long term and indirect) but it is only when a claim is closely argued, and preferably based on empirical evidence, that it become science and ready for publication in a research journal.

Peer review

Now the editor of Journal of Chemistry: Education Research and Practice may disagree with me (at least, assuming she scrutinised the article before it was published). ⁵ But supposedly this journal undertakes formal peer review – that is experts in a topic are asked to evaluate submissions for suitability for publication – not only to make a recommendation on whether something should be published, but to raise any issues that need addressing before such publication.

I wonder who reviewed this submission (were they experts in primary teacher education?) and what, if any, suggestions for revisions these referees may have made. There are a good many points where one would expect a referee to ask for something to be explained or justified or corrected (e.g., molecules and rotations in salt crystals). Some of these points should be obvious to any careful reader (like asking what exactly is the IKD model that informs this proposal, and where are different features of the model enacted in the teaching sequence?) There are also places where the authors could have been supported to hone their text to make their intended meanings clearer. (I have considerable respect for authors writing in a second language, but that is not an excuse for journal editors and production staff to ignore incorrect or confusing expressions.)

Yet, based on any peer reviews reports, and the authors' responses to them, the editor was able to decide the manuscript was ready for publication about 10 days after initial submission.

A brave conjecture?

Given that the proposal here is likely to seem, on the face of it, quite bizarre to many of those working in primary teacher education, who are charged with ensuring future primary teachers have a good grounding of the most basic scientific concepts, values and practices, and feel confident about teaching science to children, it risks being dismissed out of hand unless very closely and carefully argued.

"…the fact that there are no works related to Raman spectroscopy to work on concepts developed in experimental science class for Teacher training in Primary Education in formation, makes the proposal that is presented more important [but also puts a high burden on the proposer to make a convincing argument for the proposal]"

Morillas & Etxabe-Urbieta, 2020: 17

So, even if the editor felt that an unproved pedagogic proposal was of itself suitable to be the basis of a research article, there is much that could have been done in editorial and peer review to support the authors in improving their manuscript to give a stronger article. After all, I suspect very few academics working in initial teacher education with future primary teachers would inherently think that Raman spectroscopy is a strong candidate for adding to the curriculum, so the case needs all the argumentation, logic and evidential support it can muster if it is be taken seriously.

Work cited:

• IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). Online version (2019-) created by S. J. Chalk. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook.
• Morillas, H., & Etxabe-Urbieta, J. M. (2020). Raman Spectroscopy: A Proposal for Didactic Innovation (IKD Model) In the Experimental Science Subject of the 3rd Year of the Primary Education Degree. Journal of Chemistry: Education Research and Practice, 4(1), 17-21.
• Rajawat, J., & Jhingan, G. (2019). Chapter 1 – Mass spectroscopy. In G. Misra (Ed.), Data Processing Handbook for Complex Biological Data Sources (pp. 1-20): Academic Press.
• Schmälzlin, E., Moralejo, B., Rutowska, M., Monreal-Ibero, A., Sandin, C., Tarcea, N., Popp, L. and Roth, M.M. (2014). Raman Imaging with a Fiber-Coupled Multichannel Spectrograph. Sensors 14, no. 11: 21968-21980. https://doi.org/10.3390/s141121968
• Taber, K. S. (2012). Key concepts in chemistry. In K. S. Taber (Ed.), Teaching Secondary Chemistry (2nd ed., pp. 1-47). London: Hodder Education.
• Taber, K. S. (2019). Exploring, imagining, sharing: Early development and education in science. In D. Whitebread, V. Grau, K. Kumpulainen, M. M. McClelland, N. E. Perry, & D. Pino-Pasternak (Eds.), The SAGE Handbook of Developmental Psychology and Early Childhood Education (pp. 348-364). London: Sage.
• Xu, J., Yu, T., Zois, C. E., Cheng, J.-X., Tang, Y., Harris, A. L., & Huang, W. E. (2021). Unveiling Cancer Metabolism through Spontaneous and Coherent Raman Spectroscopy and Stable Isotope Probing. Cancers, 13(7), 1718.

Notes

¹ Throughout the paper I would have appreciated an indication of which aspects of the activity were intended purely for the education of the future teachers themselves and which aspects were meant to be modelled for future use in primary classrooms.

---

² Is spectroscopy the same as spectrometry? Strictly these terms have different meanings. According to the International Union of Pure and Applied Chemistry (IUPAC, 2019-):

• spectroscopy is "the study of physical systems by the electromagnetic radiation with which they interact or that they produce"

whereas

• "spectrometry is the measurement of such radiations as a means of obtaining information about the systems and their components."

And

• mass spectroscopy is "the study of systems by causing the formation of gaseous ions, with or without fragmentation, which are then characterized by their mass-to-charge ratios and relative abundances."
• mass spectrometry is "the branch of science dealing with all aspects of mass spectroscopes and the results obtained with these instruments"
• a mass spectrograph is "an instrument in which beams of ions are separated (analysed) according to the quotient mass/charge, and in which the deflection and intensity of the beams are recorded directly on photographic plate or film"

So that has cleared that up!

In practice the terms spectroscopy and spectrometry are often used synonymously, even in relation to mass spectrometry (e.g., Rajawat & Jhingan, 2019) which strictly does not involve the interaction of matter with radiation.

---

³ Discrete, as this would not apply to the near continuum bands of energy levels found in metals for example.

---

⁴ Although I am not convinced that rotational modes of excitation can be detected in a solid crystal.

---

⁵ The editor of a research journal is the person who makes publication decisions. However, predatory journals do not always operate like serious research journals – and it may be that sometimes these decisions are made by admin. staff and the editor's name is just used as a sop to respectability. I do not know if that is the case with this journal, but I think by any normal academic standards some very dubious editorial decisions are being made by someone!

---