When Chemists Attack

One thing I’ve noticed in my introductory chemistry classes is that students who have trouble with the class almost invariably have real troubles with math. It’s not always that they are completely unable to do math – hand some of them an equation to rearrange in terms of x and they can do it with no trouble. The problem is that these students don’t connect all that math stuff they learned in math class to anything else. In short, they don’t know that numbers mean something.

Case in point: One of the first things we go over in introductory chemistry is the concept of significant figures – the idea that when you write down a measured number, you should write it in such a way that the person reading the measurement knows how good of a measuring device was used to get the number. When you calculate with these measured numbers, your calculator often starts adding on extra digits, making the numbers look more impressive than they actually are – meaning that you need to round the numbers after doing the caclulation to reflect that.

(Example: Punching in 10.0 / 3.00 on a calculator gives you 3.333333333333333 … But the measurements really aren’t that good, and should be rounded to the same number of figures that the original measurements were known to. So the answer is rounded to 3.33 .)

Rounding should be no trouble for a college student, right? Wrong. Students can round to the nearest whole number with no problem. They can also usually round off to the nearest tenth or hundredth without much difficulty, though they are prone to merely chopping off the number rather than actually rounding – so 4.59 becomes 4.5 rather than 4.6 . But having them round to a place bigger than the ones place and all hell breaks loose.

Let’s say you estimate the cost of a project for your home, adding the estimated costs of all the parts of the project together. You come up with a total of $2576.08 . Now since this is all estimation, you decide to record the estimate to the nearest hundred dollars. You round off at the hundreds place and write down an estimated total of $2600. You don’t make those zeros in the ones and tens place go away and write the estimated cost as $26, because that would be silly – right? You’d never be able to walk into Lowe’s and buy $2600 worth of materials for $26. Yet this is precisely the mistake that altogether too many students make. They have an idea in their heads that rounding is the chopping off of numbers, and by golly they will do it – no matter whether the answer they get makes any sense or not. They don’t know that the numbers that they calculate have a meaning, and they don’t check their answers to see if they make sense.

Now these students don’t actually misround the money example I gave above (or at least I hope they don’t), but they do make exactly the same mistake with things like masses, volumes … well, anything else except money.

A typical example goes something like this. A student calculates the mass of a chemical that should be produced in a reaction. Their calculator gives them a bunch of extra digits, and they need to round the answer. Let’s say the student gets a mass of 106.75730235 grams, but the student needs to round the answer to two significant figures (that’d be the tens place in this number). The student writes down a mass of 11 grams as their answer instead of a mass of 110 grams. Yet I bet that not a one of the students that do this would accept $11 from me as a full payment if I owed them $110!

I wish I knew what to do about this. I show them examples – including the money one above. I show them the different masses in the laboratory. Some of them do figure it out, but there are a few who just can’t seem to learn that rounding isn’t just taking an axe to a number. What’s more disturbing to me (since many of these students want to go on to become nurses) is that some of them also never realize the mistake they’re making since they never check their calculations.

My wife calls it "learning in silos" – where students don’t transfer what they learn in a class to, well, anything else. They understand that dollars are represented by numbers and that the numbers mean something, but they don’t transfer that to grams. Or liters. Do we not tie numbers early enough in the schools to real things? Or do we turn math into a video game by making students use TI-83 calculators all the way from high school?

The new Kansas science standards have been posted. It looks like it’s the same as the working draft I read yesterday.

Maybe I’m missing it, but news articles on the subject say that Kansas has "redefined science". I don’t see that. I just see Kansas ignoring good science and substituting bad science when it comes to biology.

Which is worse – redefining science to include nonsense or not being able to see that nonsense is not science?

I’m a science teacher at my local technical/community college. I teach chemistry, but the teaching of all kinds of science is important to me. I follow the creation-evolution "controversy" with interest because it could affect the quality of all science teaching.

Why does Kansas hate science?

In Kansas, the state board of education has approved a new set of science standards that takes aim at the most fundamental theory of biology – evolution. The standards seek to paint evolution as a theory in trouble because of a host of imagined problems (the main one being that it doesn’t agree with the beliefs of some overly restrictive religious sects).

I’ve not been able to dig up the final draft of the standards, but I have pulled a working document from August which should be enlightening. The document starts off with a Rationale section, which explains pretty clearly that these school board members are after evolution.

We believe it is in the best interest of educating Kansas students that all students have a good working knowledge of science: particularly what defines good science, how science moves forward, what holds science back, and how to critically analyze the conclusions that scientists make. Regarding the scientific theory of biological evolution, the curriculum standards call for students to learn about the best evidence for modern evolutionary theory, but also to learn about areas where scientists
are raising scientific criticisms of the theory.

Two sentences in and already they’re mentioning "scientific criticisms" of evolutionary theory. (Yes, those are literally the first two sentences of the document.) Of all the scientific theories out there, why pick on evolutionary theory and act as if it’s the only one in trouble?

These curriculum standards reflect the Board’s objective of: 1) to help students understand the full range of scientific views that exist on this topic, 2) to enhance critical thinking and the understanding of the scientific method by encouraging students to study different and opposing scientific evidence, and 3) to ensure that science education in our state is “secular, neutral, and non-ideological.”

See that statement about the "full range of scientific views"? Those are code words for taeching creationism (which now goes under the name of "Intelligent Design&quot) instead of biology or teaching them as equivalente. What’s wrong with that? You have your pick: Either it’s discredited science (in the sense that the claims it makes have been rather thoroughly refuted over the past few hundred years) or it’s non-science (in the sense that the new claims it makes do not explain anything and are not testable). Why waste time teaching that sort of stuff in a science class that will have its hands full teaching current science?

Evolution is accepted by many scientists but questioned by some.

This statement is simply misleading. A more accurate rendition would say something like Evolution is accepted by nearly all biologists, but questioned by a tiny minority of scientists – most of which have little to no biological training. The statement is about as silly as saying that The roundness of the Earth is accpeted by many scientists, but questioned by some.

The Board has heard credible scientific testimony that indeed there are significant debates about the evidence for key aspects of chemical and biological evolutionary theory.

At the hearings that scientists refused to participate in?

All scientific theories should be approached with an open mind, studied carefully, and critically considered. We therefore think it is important and appropriate for students to know about these scientific debates and for the Science Curriculum Standards to include information about them.

There are debates about evolution, just as there are debates about the nature of the atom. But the debates are not about what the board implies. The debates about evolution aren’t over whether evolution occurs, but are largely about the relative importance of different evolutionary mechanisms. Just like a debate over the way a nucleus of an atom is held together is not a debate over whether the atom exists.

Skipping a bit…

We also emphasize that the Science Curriculum Standards do not include Intelligent Design, the scientific disagreement with the claim of many evolutionary biologists that the apparent design of living systems is an illusion. While the testimony presented at the science hearings included many advocates of Intelligent Design, these standards neither mandate nor prohibit teaching about this scientific disagreement.

We don’t mandate teaching creationism – wink, wink. And it’s a good thing that the science standards don’t mandate teaching intelligent design creationism, since not even the intelligent design creationists can figure out exactly what intelligent design creationism is. (Mostly, it’s versions of We don’t like evolution because it doesn’t completely explain every last detail of this bodily function. But Intelligent Design doesn’t provide an explanation for these details either.) They advocate teaching "criticisms" because that’s literally all they have.

Moving on, let’s see what Kansas students will hear in their biology classes.

However, in many cases the fossil record is not consistent with gradual, unbroken sequences postulated by biological evolution.

They’re actually going to teach students that the fossil evidence contradicts evolution. That’s a notion with basically no support from biologists. What they probably should say here is that the fossil record might suggest that some mechanisms of evolution are more important than others – not that the fossil record is inconsistent with evolution. Of course, that would presuppose that the school board here is trying to be honest.

The view that living things in all the major kingdoms are modified descendants of a common ancestor (described in the pattern of a branching tree) has been challenged in recent years by: i. ii. Discrepancies in the molecular evidence (e.g., differences in relatedness inferred from sequence studies of different proteins) previously thought to support that view. A fossil record that shows sudden bursts of increased complexity (the Cambrian Explosion), long periods of stasis and the absence of abundant transitional forms rather than steady gradual increases in complexity,and iii. Studies that show animals follow different rather than identical early stages of embryological development.

It’s at this point that biologists start frothing at the mouth. Why? Because these parts of the Kansas science standards read like a laundry list of discredited critiques of evolution. You can find the scientific response to all of this stuff at places like the talk.origins web site. I’ve linked in a few examples for you already.

Whether microevolution (change within a species) can be extrapolated to explain macroevolutionary changes (such as new complex organs or body plans and new biochemical systems which appear irreducibly complex) is controversial.

The keywords "irreducibly complex" are from the creationist playbook. And evolution explains those systems, too.

Also, the idea that cumulative small changes can add up to large change is hardly controversial. It’s about as controversial as a walk across the neighborhood. Humans walk slowly, and if I appear several miles from my house without my car, you probably wouldn’t have a lot of problem with me saying I walked there. Why wouldn’t you? Because even though I walk slowly, if I walk for a long time, I can go a large distance. Even though changes between generations are small, given enough time the overall change can be large. This is controversial?

Look at these quotes – from two different sections of the document.

These kinds of macroevolutionary explanations generally are not based on direct observations and often reflect historical narratives based on inferences from indirect or circumstantial evidence.

Middle level students have the capability of inferring characteristics that are not directly observable and stating their reasons for their inferences. Students need opportunities to form relationships between what they can see and their inferences of characteristics of matter. We cannot always see the products of chemical reactions, so the teacher can provide opportunities for students to measure reactants and products to build the concept of conservation of mass.

The first paragraph is from the life science part of the dicument, while the second part is from the physical science part. Why is it bad to use some indirect evidence in biology but not in chemistry?

Some of the scientific criticisms include: a A lack of empirical evidence for a "primordial soup" or a chemically hospitable pre-biotic atmosphere; b. The lack of adequate natural explanations for the genetic code, the sequences of genetic information necessary to specify life, the biochemical machinery needed to translate genetic information into functional biosystems, and the formation of proto-cells; and c. The sudden rather than gradual emergence of organisms near the time that the Earth first became habitable.

We’re hitting a little closer to my field here – chemistry. I find it fascinating that Miller/Urey-type experiments are successful at producing the building blocks of life from chemicals and conditions that were likely similar to those on the early Earth. Maybe it appeals to the mad scientist in me: Mix chemicals, add lightning. Collect the building blocks of life – amino acids. I also think that high schoolers would find it fascinating (which may have something to do with it being controversial. The teens might end up becoming scientists, of all things!

The controversy here is that the original experiments were done with slightly different conditions than we currently believe was on the early Earth. Not that big of a deal, really. There’s also a molecular structure issue dealing with how the atoms in the amino acid are arranged. (Chemists call this stereochemistry.) Life on earth uses one type of arrangement, while the Miller/Urey experiment produces two arrangements for each amino acid (a racemic mixture). I’m not really clear on why creationists see this as a problem, since some surfaces will selectively attach to one kind of amino acid but not the other (they are stereoselective). Neat stuff!

To wrap up, the Kansas science standards appear to throw science out of the window and introduce the speculation of a bunch of fringe groups as its substitute. So far, it’s mainly biology in the crosshairs. But who says that my favorite science – chemistry – isn’t going to be next?