Archive for the ‘Science education’ Category

“Not just a little bit over the line”

Tuesday, March 20th, 2007

Here’s a little public service announcement to all of you budding science teachers. If you’re a new biology teacher in a public high school, it’ll do you good to stick to teaching science.

If the article above is correct, Kris Helphinstine couldn’t last longer than eight days as a biology teacher before unleashing the crazy:

Kris Helphinstine included Biblical references in material he provided to students and gave a PowerPoint presentation that made links between evolution, Nazi Germany and Planned Parenthood.

The Biblical references were probably merely inappropriate in a high school biology class. But “links between evolution, Nazi Germany, and Planned Parenthood”? Do we really need the tinfoil-hat conspiracy crowd teaching our high schoolers? No, we don’t. The local school board felt that way, too. They fired Helphinstine:

“I think his performance was not just a little bit over the line,” board member Jeff Smith said. “It was a severe contradiction of what we trust teachers to do in our classrooms.”

In his defense, Helphinstine said that he was merely trying to teach “critical thinking”. He must have neglected to inform the students of his objectives, since they were apparently more confused by his materials than anything.

As for me, I’m not buying Helphinstine’s excuse. There is plenty of material you can use to teach “critical thinking” in science classes without loading up on the Bible, Planned Parenthood, or Nazi conspiracies. Even if his intentions were honorable***, he led his class into an educational minefield. He shouldn’t have been surprised when one of those mines went off.

***It’d be nice to see the materials used in the class. That’d help us judge his intentions.

Update: It doesn’t look so good for Helphinstine. More here

All wet

Monday, February 26th, 2007

I have often joked that, in addition to fume hoods, chemistry laboratories come equipped with giant invisible brain vacuums mounted above the door. These giant vacuums suck the common sense right out of students’ heads as they walk into the laboratory.

How else can we account for the fact that many students lose all common sense while they’re in the lab?

Here’s an example. We’re performing a specific heat lab in my introductory chemistry lab. Students heat up a metal sample by placing it into a test tube suspended in boiling water. Since the water is boiling, the metal evnetually reaches the same temperature as the boiling water: 100oC. The metal is then put into a cup which contains a known amount of room temperature water. The students then measure how much heat goes from the metal sample to the room temperature water.

The lab manual asks students a queston: Why is the metal sample placed into a test tube and then lowered into the boiling water rather than being placed directly in the boiling water?

Putting the metal sample directly into the water – obviously – gets it wet. Transferring hot water along with the metal sample to the cup will make the temperature inside the cup go up more than expected, and the energy calculated will be too large.

One student had some trouble with the answer, and asked for a hint. But the problematic part of the answer might not be what you think …

Me: So, how is the metal sample going to be affected if you put it directly into the boiling water instead of the dry test tube?

Student: I don’t know.

Me: Okay. Hmm … Let’s say you’re riding in a boat and you fall overboard. What do you get?

Student: You get … tired? From swimming?

Me: How about this? You jump into the pool. How are you different after you jump into the pool from the way you were before you jump in?

Student: You’re … wet?

Me: Good. So now all you need to think about now is how that metal sample being wet with hot water before you put it into the cup would affect your results.

Science knowledge in America

Sunday, February 18th, 2007

Good news, everyone!

A new study shows that Americans of 2005 (28%) are much more likely to understand science articles in the news than Americans of 1988 (10%). The study’s author says that the major reason is that more colleges have basic science courses as an entry requirement.

I’ll buy that line of argument. Put more people through basic science courses early, and at least some of it will stick. More people with some scientific knowledge is certainly a good thing. But there’s one little problem – there’s also the issue

that people are giving increasing credence to pseudoscience such as the visits of space aliens, lucky numbers and horoscopes.


One problem, [Carol Susan Losh of FSU] said, is that pseudoscience can speak to the meaning of life in ways that science does not.

What, does no one read Carl Sagan anymore?

I’m not sure I buy that belief in pseudoscience is up because of some sort of search for the meaning of life. Wasn’t that need just as real in the past as it is today? I might be inclined to buy into the idea that, since pseudoscience is all over the web, people are more exposed to nonsense than they ever were previously.

As silly as I think astrologers and people who claim to talk to the dead are, I don’t worry about them that much. Why? Mainly because most practitioners of pseudosciences like astrology aren’t seeding school boards with candidates to try to sneak astrology into the science classroom.

But there’s one pseudoscience out there whose practitioners can’t keep their mitts off the science curriculum. Creationism.

Back to the article …

[…] there also has been a drop in the number of people who believe evolution correctly explains the development of life on Earth and an increase in those who believe mankind was created about 10,000 years ago.

(emphasis mine)

To believe that the world / mankind was “created” six to ten thousand years ago, you have to throw away the foundations of almost all the sciences. Fundamental facts and theories in chemistry, physics, geology, biology, etc. are simply incompatible with the young Earth viewpoint.

And the numbers of these people are growing? That’s a frightening thought!

Watch where you’re pointing that thing!

Friday, February 9th, 2007

A post over at Pooflingers Anonymous reminded me of a little rant I’ve been meaning to post for a while.

Consider this lovely Pasteur pipet.

[Pasteur pipet]

The Pasteur pipet is truly a small wonder. It’s cheap, disposable, and can be used to transfer small amounts of liquid from one place to another with almost no mess. The suction from the bulb keeps the liquid inside from dripping. There’s also very little risk of contamination of sample, since the glass part is disposable – and is only used to transfer one solution.

What irritates me to no end in introductory labs, though, is one simple error that students will just keep on making over and over again – no matter how many times I point out the error and correct it. That error is …

[Pasteur pipet tip up]

… holding the pipet with the tip up.

Holding the pipet this way causes the liquid inside the pipet to run down into the rubber bulb. While the glass body of the pipet is essentially chemically inert, the rubber bulb is not. Strong acids attack the bulb, as do many solvents – and the products of these reactions get into the dispensed liquid. Any contaminant that’s present in the rubber bulb – usually caused by some other student holding the pipet with the tip up – will also get washed into the dispensed liquid.

All of these contaminants will screw up results. For students, that translates into bad grades. That, at least, is something that students should understand!

Certified: Science wins in SC … for now

Friday, November 17th, 2006

Well, it’s official. Anti-science candidate Karen Floyd has been defeated by Jim Rex for the post of SC Superintendent of Education.

This, of course, assumes that there aren’t legal challenges to the vote. We shall see.

Updated on 11/21/06: Floyd has conceded.

[Rena: It made me a little happy.  From Star Ocean: The Second Story (Playstation)]

Why only a little happy? Well, the margin of victory was only 455 votes! Rex’s opponent was not only unqualified for the office but also said such mind-bogglingly foolish things as

More and more scientists are publicly coming out in favor of an Intelligent Design Theory because that is what the evidence is telling them is true.

Long gone are the days when God was excluded from scientific circles. If we ignore that reality, we will only limit our children’s scientific knowledge.

Clearly, the theory of the politically-correct minority has been allowed to dominate our classrooms to the point where not only is evolution being taught as a scientific truth, but the public address system cannot be used to say a prayer for the safety of athletes before a football game – this is wrong.

(Source: SC PIE)

455 votes … out of a million. We’ve got a long way to go in South Carolina.

Pet peeves: Preforming an analysis

Monday, October 9th, 2006

Here’s one of my pet peeves – “preformed”. I routinely have students tell me things like

The standardization of 0.1 M base was preformed using the primary standard grade KHP.

I’m sure the student didn’t mold the base into a predeterimined shape before doing the analysis. Perhaps this student meant that they “performed” the standardization?

Of course, even the word “perform” in a description of what you’re doing in a lab is never actually necessary – unless you’re actually performing your experiment before a live studio audience. What’s wrong with saying sometihng like this?

The 0.1M NaOH solution was standardized by titrating against primary standard grade KHP.

Classics of Student Literature

Friday, October 6th, 2006

This is a collection of funny student answers from my first few years of teaching introductory chemistry classes at my college. All student answers are presented as the student submitted them to me – spelling and all. Enjoy!

It helps to know what science you’re in

Question: Briefly define chemistry.

Student answer: A systemic substanse study of matter.

Conservation of mass: When you do a chemical reaction, the total amount of mass remains constant.

Question: Briefly state the law of conservation of mass.

Student answers:

  • Mass is equal to volume. You mass something when in something. The weight how much holds or is.
  • Mass measurements can be precise or accurate. Precise ask how close are measurements to the same measurement and accuracy wants to know is it right, law wants to know can I do it again.
  • Mass is how much it takes up on an object.
  • Mass is the kilograms.

Fun with Marshmallow Peeps!

Picture a marshmallow peep floating in a beaker of water. This was sitting in front of the students when they answered the following question.

Question: Is the marshmallow peep more or less dense than water?

Student answer: No.

Fun with magnesium!

Magnesium metal burns in air with a brilliant (almost blinding) white flame and leaves a white ash behind.

Question: Describe as thoroughly as you can what happens when a piece of magnesium is burned in air.

Student answers:

  • When a piece of magnesium burn in the air it will not show a reaction b/c the air has less density and it will not burn throughly.
  • It would explore like firecrackers.
  • When a piece of magnesium burns, it gets hard and turns into a metal.

Fun with oxygen!

Students prepare molecular oxygen (O2) and investigate the effects of a pure oxygen environment on combustion. They observe that things burn more intensely in pure oxygen.

Question: How does the amount of oxygen present affect the rate of combustion?

Student answers:

  • In high oxygen things give off better reaction and combustion. Compared to low concentration of oxygen.
  • In high concentration of oxygen is faster than air.
  • Oxygen burns faster and in air it doesn’t burn.
  • The fire is more contense in oxygen. The oxygen speeds it up (fire, the burning).

Sulfur burns a with bright blue flame in a high concentration of oxygen and with a dimmer blue flame in air. The faster sulfur burns, the brighter the flame is.

Question: What evidence from the burning of sulfur confirmed your conclusion about the rate of combustion?

Student answers:

  • That the sulfur when heat was added to it. It just started crackling and burning and looked like kinda like a copper color.
  • It change from a powder form to a liquid form.
  • It turned dark and there was a liquid.
  • An environment with pure oxygen can reignite flame from embers, but low concentration can not. High oxygen content created more intense heat.

Fun with hydrogen!

Students prepare, collect, and burn hydrogen. Hydrogen burns rapidly with a loud popping sound.

Students collected hydrogen by bubbling it through a bottle of water. This works because hydrogen does not mix well with water (it’s “insoluble”) and is able to push the water out of the bottle.

Question: What physical property of hydrogen, other than it is less dense than water, allows it to be collected in this manner?

Student answers:

  • Oxygen.
  • Very reactive.
  • Because it’s lighter than air.
  • Its ability to mix with other gases “diffusion”
  • It’s a molecule found in air.
  • It is an element, reactive, and can burn and also a gas at room temperature.

You don’t get a “pop” from hydrogen combustion when you bring a burning splint over a bottle which has sat open for a full minute. The hydrogen is very light and escapes into the room.

Question: How do you account for this?

Student answers:

  • Because hydrogen is dense.
  • B/C it was left open for 1 minute + the hydrogen left out. Was oxygen.
  • Air and hydrogen in the bottle did not make a popping noise.
  • The hydrogen was at the top of the bottom.
  • Oxygen put out the flame.

Science education as Jeopardy

Friday, September 22nd, 2006

CNN is carrying a small story pointing to a report from the National Research Council on science education for young people. The press release is here.

I haven’t had time to read the full report (352 pages!), but this part of the press release resonates wilh me (bold added by me, for emphasis).

Today’s standards are still too broad, resulting in superficial coverage of science that fails to link concepts or develop them over successive grades, the report says. Teachers also need more opportunities to learn how to teach science as an integrated whole — and to diverse student populations.

A little while ago, I was briefly involved in a workshop whose goals were to try to align the courses of the high school with the courses at the college – making it easier for the high schoolers to transition to our college when they graduate. This gave me some opportunity to talk with some of the high school teachers about what sort of things were in the standards to be covered in high school science classes.

While this National Research Council is about K-8 education, I find that the high school standards suffer from the same problems: too many topics and too few underlying principles. In the mad rush to get through all the bullet points the course is supposed to cover, important concepts receive rather shallow treatment. I remember remarking at the workshop – “Wow, if my freshmen actually understood half of what’s in that list [the standards], all I’d need to do in class is pass out the test.”

My incoming students might have heard the terms “chemical reaction”, “percent yield”, and “equilibrium” Were Alex Trebek to uncover a definition of percent yield on an episode of Jeopardy, many of my incoming students might respond with “What is percent yield?” But they aren’t able to connect these concepts – because they do not see chemistry as a set of ideas linking things together. And, they don’t see science as a way of getting things done. Instead of knowing science, they know Jeopardy.

The National Research Council recommends, for K-8 students, this:

Students should have a wide variety of learning experiences in science classes, the committee said. Those experiences should include conducting investigations; sharing ideas with peers; talking and writing in specialized ways; and using mechanical, mathematical, and computer-based models. Science should be presented as a process of using evidence to build explanatory theories and models, and then checking how well the evidence supports them.

Sounds good to me, but I have my doubts as to whether a lot of this will be implemented. It’s all a matter of cost. All the stuff suggested above costs money – not just in terms of technology, but in terms of personnel. I teach classes for adults who wish to work in the chemical industry – and I try to do a lot of the stuff above with them. For it to work well, the class needs to be small – so you can have meaningful interactions with students on the concepts they’re investigating. You also need adequate technology. For schools that have trouble keeping the buildings from falling apart due to lack of funds (read: poorer districts in my state, for instance), this’ll be a tall order.

Real science is better, but Jeopardy is a lot cheaper. At least in the short term.

The many phases of iodine

Monday, September 11th, 2006

Iodine is a rather neat element. It’s a nice – if a little boring looking – crystalline solid at room temperature. Chunks of iodine are similar in appearance to things you might find in the bins of rocks at places like Black Market Minerals at Barefoot Landing.

[Solid iodine]
Solid iodine

Iodine is interesting because it is easy to make solid iodine go into the gas state. Plus, unlike many gases, iodine vapor has a distinct purple color and is easy to see. Solid iodine slowly sublimes (goes from the solid state to the vapor) at room temperature. It’s easy to accelerate this process by supplying a little heat.

If the iodine vapor comes into contact with a cool surface, it will deposit (resolidify) on the surface, forming pretty crystals. (A similar thing happens when water vapor comes into contact with a cool surface, although in that case you usually get liquid water.)

To show this, I tried to replicate a picture of a demonstration from one of my older chemistry books. I took some solid iodine and put it into a beaker, then set the beaker on a hotplate. On top of the beaker, I put a watch glass (curved piece of glass that looks something like a lens) and some ice – to provide a nice, cool surface.


To speed up the production of iodine vapor, I turned on the heat (just a little). You can just barely make out the purple iodine vapor in the beaker.

[A little iodine vapor]
A little vapor is visible

If the hotplate’s temerature gets to about 114 oC (about 237 oF), the iodine will begin to melt, forming a dark purple liquid. The amount of iodine in the vapor state goes up, too!

[More iodine vapor]
More vapor is visible. If you value your nose, keep it away from this vapor.

What’s impressive about this demonstration is the sheer number of phase changes that are going on at once.

[Phases galore!]
Pick a phase, any phase!

At the bottom of the beaker, you have some solid and liquid iodine. Since the hotplate is providing heat energy, you have the solid iodine melting and subliming. The liquid iodine is also evaporating. Near the top of the beaker (and to some extent on the sides of the beaker – which are cooler than the bottom), you have deposition of iodine vapor, forming solid iodine crystals. (It also looks like some iodine may have condensed on the hotter parts of the beaker nearer the bottom, then frozen after the beaker was removed from the hotplate.) That about covers it!

… not counting the ice, that is. The ice at the top of the beaker is melting, removing energy from the iodine vapor as it deposits on the bottom of the cold watch glass.

[Deposited crystals]
Deposited iodine crystals, forming from purple iodine vapor

The crystals formed on the watch glass are flat and shiny – almost metallic in appearance. They’ve grown to look a bit like perverted stalactites.

[Deposited crystals, closer view]
Deposited iodine crystals, closer view

A few words of caution if you attempt this experiment yourself. Iodine may look harmless (it won’t blow up on you – provided you keep it away from combustibles), but iodine solid can cause chemical burns on skin contact, and iodine vapors are very bad for the lungs. This sort of experiment needs a fume hood, and solid iodine shouldn’t be handled directly.

From the department of the obvious

Thursday, September 7th, 2006

News from the department of the obvious: Basic medical instructions hard for most adults, study finds

The subject of the article is how folks have trouble following “health instructions”, which is … not surprising in the least. We do pretty poorly in many areas of science literacy – medical science certainly isn’t an exception.

But here’s the quote that I’m going to fuss about, since I’m your friendly neighborhood chemist.

A consumer may want to know the salt content before buying, but the word salt isn’t on the label.

“Of course, they wrote ‘sodium,’ but that’s a technical term, that’s a chemistry term,” [Dr. Rima] Rudd said. “You don’t sit at the family table and say, ‘Pass the sodium please.”‘

Well of course you don’t ask someone to pass the sodium at the dinner table. Pure sodium is a soft, metallic element that reacts violently with water. It would be a decidedly bad thing to pass around at the family table. The stuff you pass around at the dinner table is a sodium-containing compound called sodium chloride.

Plus, “sodium” is hardly a more technical term than “gold”, “silver”, “iron”, or “oxygen”.

“They’re writing things at a level in the health field that is very difficult for the general public to work with,” Rudd said.

While I’d certainly agree that information leaflets that come with prescription drugs are written in a language that is difficult for someone without medical training to understand, I do not think the same thing applies to “sodium” on the side of a soup can. Anyone who makes it out of high school without enough knowledge to know a few basic things about what common table salt contains has been done a disservice.