In Praise of Alex Johnstone; He made me realise I was not alone


Our research shows that pupils at all stages were complaining about the same areas of the syllabus – energetics, the mole, balancing equations ionic equations and parts of the organic chemistry…….The factor common to all these areas was that they were being taught in a fashion which overwhelmed the short-term memory.

On realising that I am a teacher of chemistry, I am regaled by people with of tales  experiments going wrong when they were being taught. (It might be the best part to them but not to me in my role as a safety consultant with CLEAPSS.) They often add that they never understood what was going on especially with equations. I suspect that most chemistry teachers are subjected to this.

That statement at the beginning is from the Introduction of Chemistry About Us by Alex Johnsto ne, Norman Reid and Ian Morrison. It was written about 1979 (it could even be written now) and Alex was then in education research, Ian was a Local Authority Science Adviser and Norman was a teacher. In 1964, Alex, then the teacher, and Ian, the Teacher trainer, had developed Chemistry Takes Shape (Vol 1-5). They, like the some teachers in England in the Nuffield Foundation, could see that the content of the chemistry curriculum and the methods used to teach it in secondary schools had barely changed since the 19th century. Rote learning tended to mean that students understood little of what they had learnt. Students needed to experience science for themselves through practical work, rather than just reading about it.

I was at a meeting of 40 chemistry teachers about 5 years ago, having been invited to do a microscale workshop. I went into a talk by Dr (now Professor) David Read of Southampton University. David asked the teachers “How many of you have heard of Johnstone’s triangle”.


David is modern; he has electronic measuring equipment and they had to make a decision and press a button, so we saw the answer immediately. Only one teacher had heard of it. When he put the triangle on the board, you could see flashing light bulbs coming from 39 heads. In this simple diagram, Alex Johnstone encapsulated the issues of teaching chemistry. The part of chemistry that everyone loves consists of the explosions, the fire, the sparks, the sudden red-hot glows, liquefied gases and the colour changes. Chemists rank as the great entertainers of the sciences from Humphrey Davey to Dr Hal. The Royal Institution Christmas lectures seem determined to show a hydrogen balloon bursting with fire even if the subject is about language as in the 2017 Christmas lectures (see below). Getting the students to think about the interaction of particles and applying measurements and maths is far more difficult.

RI hydrogen bang

The initial impact of this triangle to the teacher is one of comfort and reassurance. To me it means “I am not alone; other teachers have the same issues as I have but we have all been afraid of uttering them as it could imply I am a bad teacher to outsiders (inspectors, observers, parents students and even the press)”.

Alex suggests that teachers tackle two sides at a time to students when introducing a new topic. It requires a huge amount of consolidated knowledge and practice to deal with all three aspects in one lesson. This is why chemistry should be revisited at regular intervals to cement and consolidate the knowledge in the long-term memory.

Of course, some like to extend the triangle to a tetrahedron. Peter Mahaffy calls the fourth point the “human element”[i].

Simple johnstone traingle
The Johsntone triangle on the left with the Mahaffy extension on the right to make it a tetrahedron

I do not think Alex would not approve of the word “elements” in this context as it would cause conflicting “noise”, with the word being used in a different context in chemistry, but he would approve of the extension. He wrote at the beginning of the last Chapter of “Energy, Chaos, and Chemical Change[ii]” which is entitled “Thermodynamics and Every Things”, published in 1977, “The work in this book will remain largely an academic exercise unless we can see it operating in the world at large.”

Here is another quote[iii] about the order in which we teach chemistry.

Begin where the students are. From an information processing point of view, begin with things that they will perceive as interesting and familiar so that there are already anchorages in their long term memory on which to attach the new knowledge. Do we begin in the traditional way with salt, sodium carbonate, silver nitrate and barium chloride OR do we begin with petrol, camping gas, plastics and foods? Organic chemistry has traditionally been thought of as too difficult for beginners, but a moment¹s thought will show that it is not necessarily so. We are beginning with the macro and can afford to take in some submicro.

In Chemistry Takes Shape, the first experiment is not about the Bunsen burner but evidence for particulate theory using purple potassium manganate(VII). This is carried on throughout the series with the model being gradually adjusted, improved and more complex, as new “macro” evidence becomes available. After introducng particles the books moves to the chemistry of oxygen, hydrogen and water but particles are always there. I notice that in a current KS3 syllabus, the particulate model is present in the first module but subsequent sections make no mention of it at all. Students will not be seeing the full picture and it will not be present in their long-term memory when it comes to further development in KS4 and post 16.

Keith Taber’s[iv] paper shows how the triangle is adjusted and improved in light of recent research. He divides the macro section (blue) into 2 because the macro concept of elements and compounds, purity etc are just as remote from students as the observed macro event. The symbolic section (green) is divided into 3. A chemical formula (C2H4) can be used to represent a substance and molecular formula. The only way I can really understand this is to redraw it myself (with extra topics) and I hope I do it justice and there will be constant debate as to whether a topic is in the right box.Taber extention of triangle

It is right to extend the idea of the triangle under the realms of research  but that will inevitably bring more complexity as seen above. That happens in chemistry itself. I can teach the chemistry of ethene quite adequately without going into complex molecular orbital theory. Similarly the original triangle might now be more limited, but it is an iconic representation of the problems facing the chemistry teacher.

So let us remember with whom it started; Alex Johnstone, 1930 -2017[v].


[ii] Energy, Chaos and Chemical Change, Heinemann Educational Publishers (1977), ISBN-13: 978-0435655259


[iv] Revisiting the chemistry triplet: drawing upon the nature of chemical knowledge and the psychology of learning to inform chemistry education, Chem. Educ. Res. Pract.,2013, 14, 156


I Give Up; Chemistry is Fun

For years, I have tried to keep practical chemistry enjoyable, but not fun. Fun is enjoyable but you do not learn anything from it. Enjoyable chemistry occurs when you have light-bulb moments, bells ring, memories come back of something you observed and could not explain, now explained. A knowing smile beams across your face. It was reinforced by a great article from Mark Lorch of Hull University.

I visited the VicePhec17 event the other week. This a meeting of University Chemistry and Physics lecturers who take education and education research seriously. I am an intruder at these meetings being a secondary (high) school chemistry and safety adviser, not an academic, but many of these University chemists are outreach officers. If school students find it difficult to get out to Universities, these people can bring Spectroscopy in Suitcases, careers advice and research advances to school students. Of course they do not do slime and H2/O2 explosions because they know that school chemistry teachers have covered all this in their lessons. Anyway, at least these outreach officers are attempting to crosslink between School and University chemistry.

I went to a VicePhec meeting 4 years ago to introduce the microscale approaches and those who came to a 1-hour workshop (nearly 20!) enjoyed it and some have use it in their teaching. So at least I am tolerated as old eccentric nerd. Much has happened since then; my attention has moved from being safety and expense orientated to improving “teaching efficiency”, “how chemistry can be explained” and making practical chemistry even more enjoyable. It was from attending Chemistry education meetings that changed my attitude. My little exhibition at VicePhec showed the paramagnetic effects on a bubble of oxygen and complexes/precipitates (video) in “puddles” as well as the propene preparation (video), electrolysis of molten lead bromide (video), the Hoffman Voltameter and the colorimeter.

My little Hofmann (3)

Lego colorimeter

But how well does practical chemistry fit with educational research? The lab bench can be very frustrating. I do spend a long time on some experiments getting them just right for teaching. Last week at CLEAPSS, Samir, our inventive physics adviser, made a well- engineered Boyles Law equipment with syringes, pressure gages and Arduino technology (STEM at its best) and I thought what about the N2O4/NO2 equilibrium at higher pressures. It initially appeared to work but then because the detector is so sensitive, it leaked very slowly so we have to think again. (Memories of the frustration of high vacuum research in 1968 flooded back!)

A lesson in a school is very tight on time, not only for teaching time but also for the preparation of chemicals and equipment, the cleaning of equipment and disposal of chemicals. When devising a procedure, whether normal or microscale, I have to think of teaching efficiency. Teachers should carefully time their lesson giving adequate time for introduction, practical time, CLEARING UP, and discussion. Everything needs to work smoothly. Have you had a lesson when a solution is not made up correctly, the tongs have been vandalised and they do not close properly or the Bunsen burners are blocked with iron filings? You know the problem; it throws you completely. This is why teaching efficiency is so important in schools. It is also a reason for me not being a great lover of completely open-ended investigations. I am also conscious overloading the short-term working memory. Robin Millar wrote[i] …a practical task should have a limited number of intended learning outcomes.  It is easy for practical tasks to become too complex, so that students get lost in the ‘noise’ of the bench.”

At these Chem Ed meetings,  there are several buzzwords at these meetings, I can erect “scaffolds”, build “platforms”, embed “MOOC with Pythons”, “blend“ and “flip and even post flip” my material. The buzzwords going around my head are “cognitive overload” and “misconception”. (Can you have an immaculate misconception?)

Now everyone seems to think practical work is “a good thing”, especially in chemistry where macro-events can be quite beautiful, startling, noisy etc. Numerous reports say we must continue. At parties and in the pub I get regaled with the most horrendous chemistry incidents with sodium and other incidents! (The following comments are usually followed about not understanding what was going on but it was fun which makes you see why I do not like that ”f” word in teaching.)

Then come those in education researchers who say practical work has a very limited effect on the understanding of the subject and countries can attain high ranking in PISA tables without doing much or having all the experiments demonstrated or on video. However, was “limited effect” a problem of a poorly designed experimental procedure? Also, it is not just chemistry but questioning any student after completing a practical element in other subjects such as modern languages, drama and history will show up short comings in understanding by that student. (I have directed school plays and opera, I know). We have to be careful here. This is music to the ear of any accountant involved in education who thinks labs and technicians are an expensive waste of time.

What I am trying to say is that the technical quality of the actual practical procedure provided needs to be researched as much as the outcomes on the student. Mixing technical issues with Chemical Education research is tricky. I sense there is  an issue with the inclusion of practical chemistry within such meetings as ICCE, ECRICE, BCCE, Chem Ed meetings. It ranges from the complete ban (safety reasons are cited but having no practical  does reduce costs in employing lab staff, using more rooms, etc) to still thinking that practical chemistry is still about big bangs, fire, sparks, working with giant soda bottles etc, and practical demonstrations are there simply to entertain. High-ranking academics and organisers of such events are often administrators (not the case at VicePhec though) rather than practicing chemists and so shunt the practical element to the side rooms or unreasonable starting times. (Poster sessions can be in the same position and I think their value is only just being realised. I prefer them rather them 15-minute rushed talk, especially if the author of the poster is present with a visible examples or equipment used. Unfortunately, many visitors take that time to have a coffee and talk about the frustrations of working life. How students learn and understand chemistry from well-directed, efficiently organised practical sessions is extremely important.

At the Hands-on Science meeting in Braga, Portugal we had a science Fair with a mixture of Portuguese academics and teachers, school and university students and a large gathering of international visitors. Some of us sat there with a table containing examples of our research and results. I had my mini experiments; no one came. The small hovercrafts, racing cars and experiments with bells, balloons etc, captured everyone’s imagination. Nothing else to do but grab attention, so I made my dynamite soap bubbles with hydrogen and oxygen from my Hofmann and lit it producing a high pitched but loud bang. The children came to see me with their teachers and parents. So I then did microelectrolysis, cracking etc as well, and I was busy for 2 hours. At the VicePhec meeting in York we had a Labsolutely Fabulous session with a mixture Chemistry, Physics lecturers interested in University education. Some of us had a bench containing examples of our research and results. I had my mini experiments; no one came. Friends were meeting each other after a year and having a chat about their jobs etc. Nothing else to do but grab attention, so I made my dynamite soap bubbles with hydrogen and oxygen from my Hofmann and lit it producing a high pitched but loud bang. The academics then came to see me. So I then did microelectrolysis, cracking etc as well, and I was busy for 2 hours.

Whether you are an adult or in your teens, you do like explosions. I give up; Chemistry is fun.

[i] Millar, R. (2004). The Role of Practical Work in the Teaching and Learning of Science. Paper prepared for the Committee: High School Science Laboratories: Role and Vision, National Academy of Sciences, Washington DC. York: University of York.

What can a Safety Data Sheet do for the chemistry teacher?

Simple Answer; “Scare you so much that you will never do any practical work with students again”. (But you could watch paint dry!)

I delivered a talk on this at the BCCE2016 at North Colorado State University in August 2016. Many people from the States commented on how different our UK safety culture is to that States. I have found it to be different to many places in Europe as well. To those of you in the UK, I must admit that CLEAPSS and SSERC  (in Scotland) are “one-off” organisations which contribute so much to the science education in the country. The UK teachers and technicians should also thank the sensible approach of our Health and Safety Executive and how our Health& safety at Work Act 1974 works. (The UK consistently has one of the lowest rates of fatal injury across the EU. In 2012 the standardised rate was 0.58 per 100, 000 workers, which compares favourably with other large economies such as France (2.64 per 100, 000 workers), Germany (0.9 per 100, 00 0 workers), Italy (1.29 per 100, 000 workers)  and Spain (1.99 per 100, 000 workers) (Eurostat, ESAW, 2012). The number in the USA is 3.3 per 100,000 workers (Bureau of Lobor Statistics)).As far as I know, although there have been some serious injuries in science education, there have been no deaths in school science lessons. However, there have been in school sporting and outward bound events but these activities are never banned.

Whenever a serious incident takes place in a school chemistry laboratory or classroom, fire and safety officers often pontificate on the incident by quoting the Safety Data Sheet (SDS). However, how many of you have read such documents in full? In UK schools we have perhaps 200 to 400 chemicals on the shelves. Have you read the SDSs for each chemical? The picture below show one educational establishment asking their students to read 7 SDS sheets before they start, ie a total of around 77 pages!

Did you even know there was such a thing


as a SDS or do you just “always read the label”. In the UK, we have many very experienced school laboratory technicians who do have access to the SDSs and to a large extent, protect the teacher and so I suspect there are some teachers who do not know that they exist.  In the EU and the USA, we have to store the MSDS sheets electronically or in a filing cabinet. I suspect once in the storage area they are never read.

SDS can be seen to be silly

This statement may seem impudent in the extreme. After all, many really well-qualified chemists and toxicologists in the United Nations, Occupational Safety & Health Administration (OSHA), European Chemical Agency (EChA), Health and Safety Executive(HSE) and countless other organisations in all the developed countries in the world have spent many hours of serious debate and research on implementing the United Nation’s Global Harmonised System. The aim is to ensure that the same information is available on chemicals no matter which continent you are in.
Yet I can show the section on sodium chloride and sterile water  to any experienced chemistry teacher and the response will be “This is silly”.

From the SDS of Sodium Chloride
From an SDS on Sterile Water

You can imagine the coffee-time discussion amongst teachers and lecturers of chemistry discussing and ultimately dismissing these documents in no uncertain terms as “unbelievable”. The issue now is that the MSDS loses its credibility amongst the experienced chemistry teachers; that can be dangerous and a complete disregard of the use of SDS is illegal.
It is obvious that a computer is at work but with companies supplying thousands of chemicals mostly to Industry, Hospitals and Universities and only a small percentage to Schools and Colleges, I hope you can see the suppliers’ problem. The format of these SDS documents are enshrined in the advice from the United Nations.

Sometimes the suppliers are not correct

UK schools have informed CLEAPSS of chemicals with any hazards which seemed to be different from those they had previously received. I remember the first one. Vaseline (usually no hazard classification) was ordered by a school from a supplier but it came with a carcinogen warning. The school contacted the educational supplier but the reply was “It is the new laws”. It was only when the school contacted CLEAPSS, worried that they had been using a substance which was carcinogenic, for tens of years with students (and on themselves!), that we managed to get the supplier to go to their supplier to confirm that her supplier did not classify substance as carcinogenic. Now, there was a reason for the hazard warning because if any supplier was taking the information from the European Chemical Agency (ECHA) website, Petrolactum or Vaseline did carry a carcinogen warning but with this comment: “The classification as a carcinogen need not apply if the full refining history is known and it can be shown that the substance from which it is produced is not a carcinogen”. This comment is easily missed. The educational suppliers have made other mistakes and poor interpretations of the law. They are learning to cope with the new legislation as it is acknowledged to be very complicated. What teachers might not realise is that a SDS is generated when the chemical enters or is manufactured in the country. The information has to be passed down to the next outfit in the supply chain and so on until your school buys the chemical. In this game of “whispers” mistakes are bound to happen.
A sole teacher in a small school was frightened to open a bottle of magnesium powder (required by an exam board for an assessed practical exam) because on the label it said H250: Catches fire spontaneously if exposed to air. Again, there had to be careful reading of the documentation because a Note said that “This substance may be marketed in a form which does not have the physical hazards as indicated by the classification”.
The UK is fortunate to have a HSE Helpline, The Environment Health & Safety Committee at the Royal Society of Chemistry and the Chemical Hazards Communication Group (industrial) for advice and help. The Health and Safety Executive (HSE) and the RSC are adamant in their support of chemistry practical work in schools. It is necessary to work with the system and not against it.

SDS can be emotive

What does the word “fatal” conjure up in your mind? “There has been a fatal accident” on the news suggests a person has immediately died but in “GHS speak”  it means very toxic. The SDS sheet for sebacoyl chloride, a chemical we use in the UK in schools to do the “nylon rope experiment” has to say the substance is fatal on contact with the skin  and CLEAPSS received a number of calls on the word “fatal” and the question “is it banned?” In fact, the degree of hazard had not changed from before GHS, but then it was written as “very toxic in contact with the skin” and nobody made a comment about that. In fact I actually poured 2 to 3 ml of this solution on my hand, washed it off and I am still here.
The hazard ratings for chemicals are not given “on the nod” but need criteria as provided in guidance in a document called the Purple Book. It does involve animal testing but one is assured this is kept to a minimum. Because of the complexity of the area, suppliers do get it wrong and if it seems wrong to you, your professional body may be the first point of call as they may have a safety section. Communicating this information to non-scientists or even scientists of a different persuasion can be difficult.

The SDS does not take into account dilution

(“The dose makes the poison” – Paracelsus)

The school buys sodium hydroxide pellets. The teacher/technician makes a solution and dilutes the solution to 0.1M. The MSDS sheet is only relevant to the person making the solution as it makes no comment about dilution. Even if you buy a dilute solution, the true hazard classification of the solution can be hidden in the wording of the SDS. I have seen SDS sheets for 0.2M sodium hydroxide which quote the hazards of solid sodium hydroxide with no mention of the reduction of hazard caused by dilution.
The teacher is left floundering as to the classification of any diluted solution. In Europe 0.2M sodium hydroxide classified as Signal Word: Warning with H319: Causes serious eye irritation. The figure below from the reverse of a CLEAPSS Hazcard (available to all schools in the UK) shows how the dilution affects the hazard of the sodium hydroxide on dilution.

Siodium hydroxide 2
These cut off concentrations differ for every substance because it is calculated by percentage by mass of substance or element present. So the dividing lines for dilution effects are different for potassium and sodium hydroxide solutions.CLEAPSS obtain these values in the European Chemical Agency (ECHA).

CLEAPSS recommends, after applying our safety regulations on risk assessment, that using sodium hydroxide solution at 0.4M (Warning) compared to 0.5M (Danger) allows the user to wear the more comfortable safety spectacles rather than the uncomfortable goggles, which are prone to misting up.

Naturally, these reductions in hazard through dilution apply to toxic chemicals. Copper(II) sulfate(VI) solutions lose the Harmful if swallowed warning at concentrations less than 1M and solutions at concentrations less than 0.6M have no hazard warning. This does not mean that teachers have a free hand to do what they like with 0.5M copper(II) sulfate(VI) solution; good laboratory etiquette is important at all times.
The changes to hazard classification with dilution are very important when it comes to carrying out risk assessments.

The SDS does not take into account exposure time

I hope you now realise that the SDS, although containing a lot of useful information, is more relevant to activities in industry where people are working with chemicals often 8-10 hours a day for a year. Obviously, in those conditions the degree of exposure is considerably higher. The word “exposure” is an unfortunate term because in law and the tabloid press, it can mean all sorts of unsavoury habits of certain individuals with weird minds. In the world of toxicology, looking at a chemical such as lead nitrate is not going to cause you a problem. Exposure means intake into the body by 3 possible routes, ie, inhalation, ingestion and through the skin (the dermal and ocular route). Some chemicals do have an immediate effect (acute); sulfur dioxide and chlorine can cause breathing difficulties but we, as teachers, should know this and apply appropriate control measures to minimise exposure. I use a microscale method of electrolysing copper chloride solution which produces less than 6 cm³ of chlorine gas in a Petri dish. If I am reacting chlorine in a gas jar with sodium or iron, I would use a fume cupboard (fumehood), which vents the gas to the atmosphere or absorbs it into a filter.

The SDS does not take into account volume and amount

Teachers may now regard with some justification that the information in relation to toxicity, both chronic and acute SDS is more relevant to industry where employees may be in contact with large amounts of material possibly as a dust or aerosol for the working day and throughout the year. This regular contact can seriously affect health.
The SDS sheet does not take into account the tiny amounts of material used by teachers and students. However, we have already seen that the information on flammability, acute toxicity, corrosion and irritation to the eyes and skin is important. Please remember that corrosion is not about rusting but the destruction of body cells.
Using smaller amounts is even more important with flammable materials. Both in the USA and UK, people have been badly burned with flammable liquids such as methanol catching fire and there are large outcries to ban the chemicals used. In the UK a boy was badly burned on the chest (made worse with a rubber lined T-shirt underneath), leaning over a tea-light. Should we ban tea-lights, candles in restaurants etc? It is constant vigilance and training on the part of the teacher, assistant and technician which matter and, more importantly, a realisation that the school-science staff need continual professional development, training etc. In the UK, senior management have a duty of care to monitor that science teachers are adhering to the rules. I don’t think they or anyone in Industry likes this, it but it is enshrined in our Health and Safety Law; it would be easier to simply blame and sack the teacher for an incident.
Teachers love teaching and they love to enthuse the students in a wonderful subject and they can easily push the boundaries too far by making a demonstration bigger. They see lecturers in lecture halls burst large balloons of hydrogen and oxygen, do “Liebig’s barking dog”, ignite large soap bubbles of methane or hydrogen (NOT LPG), in the air or  their hands, breathe in helium and sulfur hexafluoride to affect the pitch of their voices. It all looks very easy but these lecturers rehearse and rehearse these demonstrations. (I call them edutainers!) The teacher cannot simply take these demonstrations into the classroom without a lot of research, training and practice. Balloons of hydrogen and oxygen are too loud for a small room and can cause deafness, Liebig’s barking dog can explode (as it did when he did it), burning gases on the hands can cause serious burns especially if LPG is used and inhaling gases is just bad practice in a school context as it can lead to bad habits by students.

The SDS does not take into account the products of a chemical reaction

Seawater is about a 0.05M solution of sodium chloride. It is not classified as hazardous although with large exposure it can kill by ingestion of large volumes, it can be absorbed through the skin (ocean swimmers grease themselves) and breathing it in is pretty dangerous too! In the laboratory, I can put 2 carbon electrodes in sea water, connected to a low voltage supply, and generate chlorine, a highly toxic gas which can upset students with asthma. But there is no SDS for chlorine as the school does not buy the gas.
0.05 M sodium thiosulfate and 1M hydrochloric acid are not classified as hazardous but mix them together and sulfur dioxide is formed, a toxic gas. You do not have a SDS for sulfur dioxide because you do not buy it. I cite both of these experiments because they have both caused students to be taken to hospital for checks on breathing and the inevitable call from safety officers and school managers as to why we are subjecting students to distress. These were activities set by examination boards for assessment. In both cases the teachers involved were not chemists by training and the lessons got out of hand. The exam had been set by experienced chemistry specialists who knew (and probably thought all teachers knew) about the hazards of the products. The other essential part of this experiment is to pour the products of the reaction into a stop-bath of sodium carbonate solution which stops the reaction and neutralises the sulfur dioxide.
It has taken 20 years for a reduced scale method developed by CLEAPSS to be finally cited by our exam boards to be an accepted method of carrying out the reaction.

They are not risk assessments

Many articles on chemistry experiments cite hazards. The teacher should be more concerned about risk, the chances of an incident taking place and the potential severity/extent of harm that may be caused. Teachers of science need to demonstrate to senior management that they have reduced the possibility of an incident taking place and to ensure the use of the most comfortable personal protective equipment as the last resort. They can show this by including the method and relevant control measures in their schemes of work (SOW). As well as columns in SOW to please educational inspectors (eg learning objectives), there needs to be a column which shows that the teacher understands the possible risks from an activity and has taken steps (control measures) to reduce them. Both teachers and senior management should be aware that risk cannot be totally eliminated. The important factor is not to make a recorded risk assessment a huge multi-page document which will end up stored in a filing cabinet and never read (teachers do not have the time), but a few simple sentences to remind yourself (you might only do this activity once a year) and to remind your other colleagues who may take a lessons in chemistry. Lowering the concentration of a solution to a level which still illustrates what you are trying to show and has the smaller number of hazard statements is one way of showing that you applying risk assessments (hazard analysis). Teachers can add 0.4M sodium hydroxide solution to 0.1M copper(II) sulfate(VI) solution and still obtain a beautiful precipitate, instead of using 1M solutions which are far more hazardous for students to use. I can reduce the risks further by placing drops of these reagents on a plastic sheet.
If a teacher makes an improvement in safety, the SOW can be easily altered.

The teachers’ risk assessment needs to look at how the chemicals are presented to students to improve classroom management
It is important to focus on the relevant risks. In the last few years, boron compounds, used in producing green flames with methanol, have been given a hazard waning that they can cause harm to the unborn child. I have had teachers on the phone worried sick that they have used boric acid when they themselves or the students are of child-bearing age. The fact that methanol is very flammable, as highlighted in a recent report by the USA Chemical Safety Bureau into serious fires in schools, is never considered as the main risk. Many chemical text highlight the toxicity rather than the flammability. Yes it can be stolen, sold as cheap vodka and drink by addicts but this is a low risk in a school compared to its flammability. Teachers in the UK can contact CLEAPSS or SSERC  in the UK for a safe version of rainbow flames but our risk assessment uses ethanol (less toxic) and around 6 ml per beaker (reduce volume).

it is also interesting that if there is a chemistry incident, there is move to ban the use and procedure. If a student is injured playing rugby, hockey, American Football, cricket, baseball, climbing rocks, skiing etc, is there an outcry to ban these activities. Doctors who speak up are criticised as scare-mongering, stopping fun etc. If I say in some in countries that you can melt 0.5g of lead or demonstrate the remarkable nature of mercury in the open lab some people raise their hands in horror. But I  have done a risk assessment; convincing non-chemists is very difficult though.

You need training in how to use them

The teacher may be involved with over 400 chemicals in the year used in small amounts, for a few minutes and perhaps once a year. The industrial worker may be involved with 2 chemicals used in tonnes and litres (gallons) for the whole working year. The chemistry teacher might carry out 400 single operations with hazardous chemicals in the year. The industrial worker might carry out only 2 hazardous operations but they are repeated daily and all through the year. Both situations have their dangers in complacency.
It often comes as a surprise to both teachers and educational managers that risk assessment or hazard analysis is important for any work with hazardous chemicals with the MAIN findings recorded.
The problem with safety training is that it can, in the hands of some, be a frightening list of ‘don’t do this’ and ‘don’t do that’. It can sometimes be over-emotive and worst of all, patronising. Safety training works best when it shows how procedures should be carried out and then by monitoring in a sensitive manner.

A local Health and Safety Officer from the Armed Forces, Chief Fire Brigade officer, an expert in Heavy Lifting and grave digging and, dare I say it, large-scale chemistry engineering or a recent graduate in science is not always the right person to deliver this training to teachers of chemistry.
So back to that experiment on hydrolysis of tert butyl chloride.The photo below shows a  slide describing the volumes used in the experiment. Does really reading the SDS for these chemicals help the student?

SDS Capture 6