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Rethinking High School Curriculum: Chemistry

Uploaded: May 22, 2016
Q: For cleaning and disinfecting, what are the differences between soap, household ammonia, alcohol and chlorine bleach? Explain in terms of how they work.

I have asked this question of high school students who have recently completed a college-prep course in chemistry, and of adults with backgrounds in science. Excepting professional chemists. none could provide a competent answer beyond how bleach worked. When I graduated from high school, I could answer only two parts of this question.(foot#1)

This is an example of a large debate about various subject curriculum being badly outdated. Most of that debate revolves around what skills they need for jobs. But that misses a significant portion of the knowledge students need to acquire.

Continuing with Chemistry, my high school Chemistry classes were heavily oriented toward the knowledge and skills needed by someone who would work in a Chemistry lab. Virtually all of that was irrelevant shortly after I graduated. This was the late 1960s but from what I hear, some of the details have changed, but the problem is the same.(foot#2) New York State high schools at that time had a two track system. One was for college-bound students--their "Regents' Diploma" involved a curriculum promulgated by the State with a series of state-wide exams on that curriculum. The second track led to a "local diploma" that still required a broad range of courses, but that allowed alternative courses and variations. For example, that track's Chemistry course focused on chemistry that one encountered in everyday life: in the home, workplace, community ... My recollection is that the textbook was mediocre, but there were situations where the course could actually be both interesting and useful. The critical factor seemed to be having a teacher who was a non-young woman with a background in Chemistry, not an Education major who took a couple of dumbed-down Chemistry courses to become certified in that subject. Those teachers used their personal experiences to create a course by remembering where knowing the chemistry helped them in a situation or where others got into problems because they didn't know.

One area of everyday life where Chemistry plays a big role is cooking, and there are a variety of books on this. Foremost are the books by former Palo Alto resident (now of SF) Harold McGee, aka "The Curious Cook", including "On Food and Cooking: The Science and Lore of the Kitchen" (Amazon link) and "The Curious Cook: More Kitchen Science and Lore" (Amazon link). McGee and his books get cited in popular culture, for example an episode of the TV series "Bones".
Commenters: feel free to recommend other books on the science of cooking--I know that there are several dedicated to baking that provide a better treatment than the corresponding chapters in McGee's books. But that isn't the focus here.

One argument made for keeping chemistry lab work in the high school curriculum is that it teaches important skills--carefully following instructions for a specific task, precision of names (small differences in names can have dramatic/disastrous results), and adhering to basic, underlying safety rules. While these skills are part of various other subjects, the argument is that they don't have anywhere near the level of consequences--the student may learn how to do it, but not learn the importance of doing it. For example, in writing a computer program, failure to follow instructions or being imprecise in the names is easily fixed with a few edits. And failure to produce safe programs is routinely rewarded: shortcuts transfer cost to unsuspecting customers.

Another of the goals of laboratory exercises is to impress upon the student that reality is much more complex and messy than the impressions given by the textbooks and lectures. A simple example of this comes from a friend who had made fruit gelatin salad and garnished it with slices of kiwi fruit, and when she went to put it on the table found the slices floating in pools. Previously she had successfully made this dish, but that was using "vegetarian gelatin". However, conventional gelatin (Jello-type) is protein-based, and those proteins are broken down by the enzymes in the kiwi, and fresh pineapple ... Another (messy) exception: canned pineapple is OK--the canning process destroys the enzymes.

There are similar questions about the high school mathematics curriculum. For example, there are active discussions about replacing Calculus with categories of mathematics that are more likely to be used in Information Technology careers. My personal experience was that I never used Calculus outside that course and several required college courses (Physics, Signals Processing ...). Similarly questions are being raised about Algebra. Although I routinely did algebraic transformations throughout my career, some of the ones that my high school course spent significant time on were rarely used (for example, factoring polynomials).(foot#3) I chose not to use the Math Curriculum as the example here because there is already an extensive discussion on this, and (unfortunately) many of the participants assume, without evidence, that their own personal experience is typical.

The issue of updating the high school curriculum comes up frequently, and at some point it might actually happen. To understand why a change can be so difficult, you need to recognize the political and pedagogical issues. The fundamental political problem derives from inertia (social, not physics). The colleges have their expectations of what well-prepared students should know, and the testing companies market exams support those assumptions (for example, the SAT Achievement Tests). Consequently, for many students and parents, the course that best prepares the students for their future is not one that imparts knowledge that they will actually use but one that better prepares them for an exam that may determine which colleges they go to.

On the pedagogical side, you need to worry about having enough breadth and depth of what is covered--finding good example of enough of what needs to be covered can be difficult. Let me emphasize that: It is much harder than simply combining a set of facts into a lecture and declaring them "learned" because the students can remember enough of them on a subsequent test. Because the repetitions during the course may not be enough for long-term retention of the lessons, having the teaching examples correspond to everyday life has the decided advantage that there will be ongoing repetitions.(foot#4) However, the logistics can be problematic. There is the logistics of individual classes, and the logistics of scaling up a course offering so that it isn't dependent on particular individuals and related circumstances.

Another candidate for more course content is evaluating the science behind current events. Unfortunately, finding such topics that won't offend someone's politics can be difficult.

Caveat: One of the problems with updating a curriculum is that many of those involved can see only a small portion of the problem: Today's students are intimately aware of the course content and the short-term effectiveness of the teaching, but don't know what the future will bring (despite beliefs to the contrary). By the time they become parents of high school students, much of their experience will be obsolete. My experience with the education professionals is that they have such a different experiences, priorities and vocabulary that it is hard to understand each other's perspectives--just think about how different the workplace of a high school teacher or university professor is from most.

Note: My professional background is Information Technology, not Chemistry. But this blog is not about the details of a High School Chemistry curriculum, but of the general direction of one.

1. Informal, partial answer: Soap can be thought of as a molecule with one end that binds to oils and greases and the other end that binds to water. For soap to be effective, it needs to be pushed into good contact with the oils and then flushed with water to pull away the oil/grease that the soap molecules have grabbed onto. Sudsing--bubbles--helps with separating and carrying away the soap and what it has latched onto. The role of hot water is to soften up greases to make them easier to pull away.
Soap "disinfects" by removing the oils that were holding in place the germs...
"Detergents" operate in the same manner, and the use of this word can be ambiguous: Some include soaps as a subset of "detergent" and some use "detergent" for the non-soap substances that act in this manner.
Practical: If you mistakenly think of soap as dissolving oils rather than yanking them away, notice how this affects how you wash your hands. And how you understand the admonition to not overload a washing machine.
Household ammonia interacts with greases to form soaps that are then easily flushed away.
Chlorine bleach is a very aggressive oxidizer--it rips apart many other molecules. Warning: Don't mix chlorine bleach with ammonia (and similar chemicals): It is very dangerous.
Alcohol disinfects by disrupting various cellular functions, depending on the concentration used and the type: methanol ("wood"), ethanol, propanol ("isopropyl", "rubbing")...
"Extra credit": Other/alternative cleaning products such as vinegar and baking soda. "Extra credit": What works better in different cleaning situations, such as windows and greasy pans.

2. How times have changed: Could it be that HS Chemistry Lab is more relevant for those not intending to go to college? In the TV series "Breaking Bad", some of the early episodes revolved around using old-fashioned Chemistry Lab skills for superior manufacturing of Meth (methamphetamine). However, this series didn't produce an observed uptick in HS Chemistry class enrollments in areas with widespread Meth manufacturing. So much for the influence of TV.

3. When and where I was a student, Algebra was the watershed course between "math" as calculation (arithmetic) and math as representation, with algebraic transformation being the means to simplify (or clarify) the original representation into something that was practical to solve. Additionally it taught that there wasn't a simple mechanical recipe for solving a given problem, but rather a set of tools that you needed to choose between, with some of them turning out to not be helpful.

4. The problem of retention has long been recognized. My favorite studies are ones that repeat end-of-school-year exams at the beginning of the next year. These experiments find large losses, for example, students who got As on the test at the end of the course get a failing grade on the test administered after summer vacation. Part of this effect is due to what is being tested: When I was teaching, some of my test questions would be about things that a student who had done the homework would have had enough repetitions to remember at that moment. They weren't specific things that I expected the students to permanently remember, but rather proxies for a range of things the student should have learned by doing the homework.


An abbreviated index by topic and chronologically is available.

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Posted by Max Hauser, a resident of Mountain View,
on May 22, 2016 at 10:45 am

Max Hauser is a registered user.

First thought: A change from your usual (policy-mechanics) subject matter. Second thought: A good, thought-provoking subject! (Got a great laugh from Footnote 2.) Some comments:

1. Great point about everyday relevance of basic ideas available from high-school chemistry. If more people had those intuitions, then among other effects, consumer-product makers wouldn't need evasive euphemisms (listing a salt additive as "yellow Prussiate of soda," making up the acronym "Niacin") when the standard chemical terms today frighten people via anxious mistaken assumptions. Folks might never have leapt into the trap of self-diagnosing food sensitivities as "MSG allergy" (MSG is, effectively, present throughout our bodies anyway, and also is part of the flavors of many natural foods). People anxious over "chemicals" in their environment, or in food ingredients lists, might instead learn about the ones that make up themselves.

2. Harold McGee's book is a valuable one-volume food reference, justly praised. However on food *science* it has limitations. People with relevant science backgrounds are sometimes surprised at explanations, omissions, etc. in it and his other writings. Among several examples, I recall a column portraying as a newsworthy discovery the attribution of Champagne bubbles to "nucleation loci." But that's just generic standard science language for the places where things like bubbles start; it doesn't *explain* the process at all. Scientists have remarked on beverage-bubble nucleation for, literally, generations. That was like proclaiming the cause of white hair to be foliculary albinism (which means, "white hair"). Keep in mind that McGee's degrees are in literature, not science.

3. Algebra and calculus may not be used day-to-day in "Information Technology" careers (as in a relatively self-contained subject like software), but they're foundations of most higher math, vital to all sorts of applied science and engineering. There's also the argument of the humanities scholar Richard Mitchell (the late "Underground Grammarian," gadfly critic of modern education's failings) that "mathematics doesn't just make sense, it makes sense happen in those who contemplate it" -- i.e., expands our intuition in new directions, broadening our mental equipment for dealing with the new and the unknown.

Posted by Douglas Moran, a Palo Alto Online blogger,
on May 22, 2016 at 2:06 pm

Douglas Moran is a registered user.

In discussing curriculum, recognize that what a subject is about, what is taught and what is learned can be very different.

For example, Calculus may be a foundation of most higher math, but that is not what most high school students (recent and ancient) experience. Rather most of what was taught/learned was a toolbox of manipulations that they don't use in their college majors or in their careers. The arguments about Calculus in the curriculum is about whether the students' time would be better spent learning other types of math -- math that would better serve the Richard Mitchell quote and explanation in Max Hauser's comment.

Posted by Dan, a resident of Midtown,
on May 22, 2016 at 10:33 pm

This sounds like an argument for more "laning", including a vocational track. It is true that many students don't need, won't ever use and in fact probably won't really understand the significance of calculus, chemistry, physics, biology, etc. beyond the basic mechanics of solving rote problems memorized for a test. Speaking as someone who didn't have the benefit of taking calculus in high school (my school didn't offer it), I was absolutely astounded freshman year in college to find out how much easier it was to comprehend physics , engineering, economics and a whole host of other fields once I had a better understanding of mathematics... and I mean the abstract concepts, not just rules for calculating integrals. We once spent more than a month of lectures proving that Lebesgue integrals converge... still didn't know how to actually perform the integration though. Meanwhile engineering majors went through applied math and it seemed learned little more than a bag of tricks to solve integration problems. Although I don't use daily most of the advanced mathematics and physics I studied on through graduate school, these have greatly enriched my understanding of many areas in science and engineering. Knowing the limits of what I learned and having access to the internet makes it possible to fill in a lot of things that someone with a more vocational educational background would never even stop to consider. For example, where would they even get the curiosity to wonder about the difference between types of cleaning agents? Life would be far less rich if I had been limited to "applied" subjects from as early as high school. Believe it or not you can learn a lot about being an electrician , plumber, construction worker in a science lab working on fundamental research. Deep educational background in the fundamental subjects also helps you assist your children make connections between various concepts that they are learning but won't really understand "why" until later. As my son goes through the beginning of more advanced topics , I have flashbacks of all those years of education. He won't see the connections between everything he is learning for many years.

Posted by Douglas Moran, a Palo Alto Online blogger,
on May 22, 2016 at 11:17 pm

Douglas Moran is a registered user.

Thinking about more effective teaching is not "laning".

For decades, various studies into why so many students, especially girls and women, drop out of science and math have said that a top reason is that those students can't see a connection to real life. There are various reports about colleges improving retention and success rates by using more real-world/intuitive situations as teaching/homework examples (Note: they were reports of observed changes, and not well-designed experiments).

Recognize that not everyone learns the same way and excluding large groups of students who don't learn in the proscribed manner is its own version of "laning".

When I was an undergrad (early 1970s), Theoretical Math and Nuclear Physics were unabashedly accepting of bad to abysmal teaching under the rationalization that it filtered out all but the very best students--the ones that didn't need a competent teacher to learn the material. Stories of horrendous math teachers abounded. One of my professors told of taking a grad course from one of the math greats and recounted how the students arranged to have the room for 2 hours after the lecture so that they could collectively try to figure out what had been said. She said that one could tell who were going to be the next generation of greats because they were often leading the discussion. The slower members of the group became merely full professors at places like MIT.

The goal of schools should be to develop talent, not to simple be identifying it.

Posted by Dan, a resident of Midtown,
on May 23, 2016 at 3:26 pm


Now you are talking about quality of teaching. I thought you were discussing curriculum rather than quality of teaching. To me these are separate issues only tangentially related in that a teacher can't effectively teach a curriculum that they themselves don't fully understand. No one will argue against the need for quality teaching at all levels. Some people are just natural teachers and will work hard to formulate even abstract concepts into a lesson plan each student can understand in their own way. I missed taking freshman physics taught by Richard Feynman by a couple of years. Feynman was an example of someone who knew his material and was a highly effective teacher too. You are not really an effective teacher if you can't reformulate the material on-the-fly to explain it to a broader range of students. Of course it gets harder the larger the class size one is dealing with. Funny story ... HR person trying to do a technical phone screen from a script provided by a software engineer asks a software configuration question. Interviewee responds with a detailed answer of multiple possible scenarios, but not the one the HR person had written down on the paper. No way to make further progress because the HR person only knows the exact answer which is written on the paper and the interviewee doesn't know the particular "word(s)" they are looking for.

I was using "proscribed" in an interview rollup yesterday and stopped to check ... was surprised to realize it means "forbidden" instead of "recommended". life long re-learning...

"Recognize that not everyone learns the same way and excluding large groups of students who don't learn in the proscribed manner is its own version of "laning".

Posted by Douglas Moran, a Palo Alto Online blogger,
on May 23, 2016 at 4:15 pm

Douglas Moran is a registered user.

"Curriculum" is a loosely defined term. It may mean as little as an unordered list the subject matter to be covered. Or it may involve the sequence in which the topics are covered -- reflecting experience with what tends to work best for most students -- and the goals of the course or sequence of courses, that is, what is desired to have the student learn.

This latter sense includes "quality of teaching" in that the planning takes into account what is required to have effective teaching. My sense is that the curriculum should make it easy for a competent teacher to be good teacher. If it takes a great teacher to be effective, I place the blame on the curriculum, not the less-than-great teachers.

For example, I took two very bad graduate math courses where the "teacher" spent the first two-thirds of the course working through what were at best loosely connected theorems and lemmas, with no sense why these were chosen. Then at the beginning of one class meeting, he wrote the theorem that was the intended core of the course, then wrote "By the previous theorems and lemmas" and without the slightest discussion moved on.

Since this was no a deficiency of the individual "teacher" but was rather a characteristic of that Math department and many others, I regard this as a basic flaw in the goals of curriculum (stronger sense).

On "proscribed" -- thank you. I meant to indicate an instructional approach that was regarded as the (only?) correct way to teach a particular course/subject.

Posted by Reader, a resident of another community,
on May 23, 2016 at 6:12 pm

The correct word is "prescribed" not "proscribed."

Posted by sunshine, a resident of Barron Park,
on May 24, 2016 at 2:00 pm

Other books I recommend and have found very useful:
Cooking for Geeks, Jeff Potter, O'Reilly (pub), 2010
Ratio, Michael Ruhlman, Scribner (pub), 2009
Chemistry Connections, Kerry K Karukstis and Gerald R Van Hecke, Harcourt / Academic Press, 2000

For example, sugar is soluble in water, therefore when sugar has caramelized on the bottom of a pan, simply add water and walk away until tomorrow.
For a residue of oil or fat, after you have poured off most of it (I hope you pour it into a container (empty can) and save it in the refrigerator until you can dispose of it in the garbage.), add baking soda and a small amount of water, then walk away. When you return the next day the grease will have reacted with the base in the baking soda to form soap which is easily washed away.

Some of the older household help books on cleaning also have similar helpful suggestions.

Writing a computer program doesn't compare in my book with following instructions, including all safety rules in the lab. A mistake in a computer program is annoying and may cause a new product to fail, but it is not likely to result in blindness or serious injury which disobeying safety rules in chem lab may.

My recommendation would be to gradually introduce algebraic concepts before high school so that students can get away from the rote memorization and rapid recall of isolated facts earlier. I know several people for whom the rote retrieval of multiplication tables out of order or rapid addition of a column of numbers is difficult. They will find the answer if given a bit of time to work it out, but are generally not the first in the class to come up with a correct answer. However, these same persons suddenly found math fun when they entered the world of algebra and geometry (assuming the teacher is not one who insists on rote memorization of geometric theorems exactly as written in the book). Trigonometry functions are also useful in real life outside of school. I have used parts of these courses throughout my life, whereas for rapid retrieval of basic math results I rely on a calculator. Assuming I enter the numbers correctly, the correct answer appears quickly.
Algebra is also a quick way to organize your thoughts and the actions required by the calculation in a meaningful way. Based on this equation that you generated you can know what happens to one parameter if you double the value or amount of another.

As a retired chemistry teacher (beyond high school) and lab research person I find many teachers below university level lacking in science. Instructors at Community colleges and Universities are required to have a degree in the subject taught.
Some notable efforts (I'm not certain whether any of the items have been passed onto the education community at large) have been funded by NASA and NSA. The ones run by NASA often used examples from space science to capture the interest of K-12 students and presented activities that encouraged students to experience what might happen. Those of NSA I found more interesting and useful as they looked at ways to engage students and capture their interest with examples drawn from ordinary experience. (Note: one of the examples given for the NASA program involved having students stand on their heads. I could just not picture the adult multicultural students in some of my classes standing on their heads in class.)
The Royal Institute of Chemistry (UK) published some books of things students could try with ordinary household materials. Some of the labs involved building baking soda rockets and color changes using things likely to be found in the home, for example, beets or rose petals or dark green vegetables with baking soda and vinegar. Separation by chromatography can be demonstrated with a marker pens, art paper, and a small jar containing 1/4 inch of rubbing alcohol. Note: black ink works best.

Posted by AJ, a resident of Green Acres,
on May 28, 2016 at 11:02 am

Very good question from the high school students. I would further add to your thoughtful discussion that much of the deep knowledge about these things gets squirreled away behind closed doors, as surfactant chemists tend to get snapped up by companies who guard their knowledge (and scientists).

From professionals willing to talk, advice for disinfection is to use a two-step process to first clean, then use disinfectants. Cleaners combined with disinfectants is a concession to human imperfection/laziness, not because it's a best practice, just as handsanitizers are a concession to human imperfection - not letting the perfect be the enemy of the good - when handwashing is per research a superior way to reduce spread of disease. It doesn't help hygiene much if doctors won't do it.

(There's what happens in a lab, and what people will do. The overall issue is public health, not just whether one thing is better than another at the sink. That said, it would be really nice if medical centers provided doctors with better than splash-prone teeny tiny sinks with spigots so close to basin sides that it's difficult to wash well without picking up more germs from the sink. One doctor pointed out to me that when some people use the alcohol-based hand sanitizers too much, they can also absorb significant amounts of alcohol. The alternative is to absorb significant amounts of whatever chemicals are in the sanitizers. Better for their health and for reducing spread of infection might be to create easier ways for doctors to wash their hands, including better and more available washing stations/sinks and products that aren't as destructive to skin.)

The efficacy of detergents and soaps (for mechanical removal of germs) is also significantly influenced by water hardness, soaps being more efficacious in soft water than typical detergents, and detergents being more efficacious in hard water than typical soaps. In my observation, water hardness is probably the biggest factor in whether soaps and detergents work well, well above most other factors for most products. I do not know how, if at all, water hardness affects the efficacy of disinfectants like bleach. Since bleach is basic (high pH), it would tend to increase the efficacy of soap but not necessarily detergents.

Strong detergents themselves have impacts beyond just cleaning - they have a powerful impact on the permeability of membranes that can be antiviral. For example, adding detergents is an important antiviral step in preparing fractionated blood products for safe use (they are mostly removed since powerful detergents equally can significantly increase human membrane permeability. Note: the detergent step is being replaced in some manufacturers' products).

Disinfection is also not a monolithic issue. Some disinfectants do a better job with some classes of microbes. Fungal organisms are notoriously difficult to clean and kill, for example, and alcohol in some instances may do nothing or provide food for the organisms. Recent studies on alcohol in certain medical settings also give a mixed bag.

All disinfectants can react with materials and create chemical byproducts, where soaps and detergents may react with the ions like calcium in the water and form "scum" but not react with other materials. Washing first, among other things, allows for reduced use of powerful disinfectants and possibly reduced chance for resistant strains to develop.

Posted by AJ, a resident of Green Acres,
on May 28, 2016 at 11:07 am

I would love to know what you think of the new disinfectant ozonated water hand sprayers - I've seen them used in some food service applications. Ozone tends to be preferred more in Europe from what I understand, and chlorine bleach more here. I have seen claims about the sprayers and how much safer they are, but nothing beyond manufacturers' claims.

Posted by Isabella Cohen, a resident of Green Acres,
on Jun 8, 2016 at 6:17 am

It has always been a problem and I suppose it will always be. Times change but the curriculum doesn't or at least not that fast. In my opinion we should update learning materials more often, add things that are practical, that can help our children go through life and perhaps remove very specific knowledge. When someone chooses e.g. career in chemistry they will learn it and get to know it anyway but if one decided to be a a painter or a librarian or museum curator then why? Also Douglas, I love the very first question of your article.


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