Lactose Intolerance

Head on over to Carl Zimmer's Loom to read up on the latest research investigating the origins of lactase persistence, the (relatively rare on a global scale) alternative to lactose intolerance, which is actually the norm perhaps for most of human history and most of the world outside of Northern/Central Europe and its colonies, and a few isolated regions of Africa.

The central question is whether herding peoples of these different regions developed lactase persistence when milk became a reliable source of nutrition, or whether pre-existing lactase persistence (for whatever reason it might have become common in a small, isolated population) led people who had this mutation to become herders.

I'll tease you with the data being collected and then you'll have to read the rest of the story at the Loom. Scientists are testing human remains thousands of years in age from different parts of Europe, some dating as far back as 8,000 years. This is roughly within the range of dates given for the time that evidence exists of herding behavior in Europe. So make your own hypothesis here - would you expect to find the gene for lactase persistence in these specimens or not? Now go find the answer.

As If..

The problem with these self-tests is that what you want to do and what you actually have an aptitude for are often 2 or more different things...

Your Dominant Intelligence is Logical-Mathematical Intelligence

You are great at finding patterns and relationships between things. Always curious about how things work, you love to set up experiments. You need for the world to make sense - and are good at making sense of it. You have a head for numbers and math ... and you can solve almost any logic puzzle. You would make a great scientist, engineer, computer programmer, researcher, accountant, or mathematician.

What Kind of Intelligence Do You Have?

A lot of wishful thinking on my part along with some forced either/or questions that can't possibly capture nuance and the complex nature of our personalities. Just for fun, don't take it too seriously. And avoid the other "tests" on the page that ask for your cell phone number.

via Evolving Thoughts

Third Lab

I just lost a long post on this lab that I was composing when IE froze up. I thought I had copied it to paste (as I usually do, just in case, when a post reaches a certain length) but apparently I messed that up to and I just don't have the patience to recreate the damned thing. So without much comment, here's a third lab. Just as a caveat, as with the others, it is somewhat untested and will undergo revisions but I'm fairly confident with 3/4th of it - not sure mealworms are capable of being trained as this lab attempts, but it'll be interesting trying.

Mealworm Behavior Lab

Go Me...

Feeling a little whimsical today.

Fathers of non-identical twins have better sperm

Of course I'm only about 90% sure my twins are fraternal and the study suffers from small sample size, but hey, I'll take any self-esteem boost I can get!

Edutopia Gets it Wrong

A recent article in Edutopia tackles the nature of science question. The author, Christopher Thomas Scott, attempts to distinguish between facts, theories, and laws, but bungles it in a way that just adds to creationists' confusion about evolution's place in biology:

We don't yet talk about the law of evolution, because the theory is still being refined and polished.

No, no, no! For comparison, here's the National Academy of Science's definition of terms that should inform all such discussions about the nature of science (emphasis mine):

Glossary of Terms Used in Teaching About the Nature of Science

• Fact: In science, an observation that has been repeatedly confirmed.
• Law: A descriptive generalization about how some aspect of the natural world behaves under stated circumstances.
• Hypothesis: A testable statement about the natural world that can be used to build more complex inferences and explanations.
• Theory: In science, a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.

As I repeatedly stress with my students, theories do not grow up to become laws. Think about it, Newton's Laws did not become laws after decades of testing and refinement, they sprang from his mind as laws because they are descriptive in nature - they do not explain WHY or HOW bodies in motion tend to stay in motion, e.g., simply that they do under prescribed circumstances (no external forces working against their motion). Another important aspect of laws is that they tend to be stated mathematically. Since we are describing nature, we can usually quantify these observations - for all the words we use to teach Newton's laws, at least in the lower grades, it all boils down to f=ma.

On the other hand, as the NAS definition of theory suggests, there are many laws that are Incorporated into the theory of evolution - for example, Darwin himself referred to the major components of his theory of natural selection as laws: reproduction & growth, variability, overproduction of offspring, struggle for survival, etc. (Source)

Part of the confusion arises, perhaps, from the fact that both theories and laws (and hypotheses for that matter) are inductive propositions. They both look at a limited, imperfect, set of data and infer order and predictability on a larger scale. From this derives the caveat that all scientific knowledge, both theories and laws (and to a lesser degree "facts" themselves), are "tentative" and subject to refinement or dismissal.

A final point about terminology - "scientists" aren't particularly hung up on these sometimes hair-splitting debates, they are too busy DOING science, while the ID crowd, conversely, spend all their time (and money) trying to confuse people with words and doing no science whatsoever to support their so-called "theory."

UPDATE


This article in the same issue by the same author is a lot more satisfying.

Two New Labs

I've started a list in the sidebar for labs that I've either created or adapted from other sources. I will slowly add to the list as I format them to a standardized layout, which takes some time. I have a number of labs that I created/adapted over the years on an ad hoc basis, usually in a hurry and devoid of an overall plan. I do think that students benefit, if we are going to do narrowly focused, traditional labs, from a standard design.

I also believe, in defense of traditional labs, that they have a place even in an inquiry classroom when done well - not that I worry anymore about what labels are applied to my teaching style - it is what it is, to borrow a cliche, and I've developed and continue to develop strategies that I feel are most helpful to my students in achieving three goals; 1. Understanding the nature of science, 2. Understanding the importance of biology to their everyday lives and their sense of place in the world, and 3. Passing the regents exam. Depending on the topic and the time of year, one of those goals may take priority over others, although they often overlap.

I'm starting the list with 2 labs that I just created to go along with the Hot Tub Mystery that we are working on. For the record, I consider the case study approach to be a good example of guided inquiry, and these labs are designed specifically to address issues that come up in trying to solve the mystery.

A final note about these labs. They are designed for lower level (8th, 9th, 10th grade) students who would be considered in a college course, "non-science majors." No slight is intended - my school simply attracts students with strong arts & humanities leanings and only a small minority are even considering the sciences as a possible career avenue, although many are clearly up to the task if they change their minds one day. Additionally, although the physical facilities at my school are fabulous, they are new and science materials to actually use in the labs are a bit skimpy. So I look for labs that are simple, require minimal specialized equipment, and can be done in a limited amount of time.

These labs have not been "peer reviewed." If you use them and find mistakes or better ways of doing some aspect of a lab, please let me know.

Cardiac Output Lab

Arteriolar Radius and Blood Pressure Lab

UPDATE 3/3/07

I finished the cardiac output lab with my classes and made a couple of adjustments. There's a certain "duh" factor to the relationship if you can visualize the process or comprehend the mathematical formula, but that's just it with kids, especially in this age group. They still need concrete experiences with these concepts and this activity is as close as I can get to a reasonable model using everyday, inexpensive, and simple materials.

I've incorporated a virtual metronome to keep the tempo and the beat for this activity - you could just have a student in the group keep the tempo with a 4 count, but I think the metronome makes the lab a little more fun and consistent as well. I like this one, GiveMe Tac! because it lets you adjust tempo, beat, sound effect. There are others that you don't have to download, like this one: Metronome Online.

Updated Cardiac Output Lab

Stiff

At the end of chapter 3, "Life after Death," Mary Roach writes"

Life contains these things: leakage and wickage and discharge, pus and snot and slime and gleet. We are biology. We are reminded of this at the beginning and the end, at birth and at death. In between we do what we can to forget.

That is in essence a partial apologia for writing a book about death and the after-death in case you were wondering why anyone would want to write such a book. Metaphysical reasons aside, the author also considers the ethical implications and dilemmas in donating one's cadaver to scientific research, a self-less act if ever there were one.

Just to lay it out for you, there are three or so basic options for what do do with yourself after you die: 1. You can donate your body to science and have it subjected to various unpleasant experiences that you don't want to know about before you die and your family won't want to know about after the fact. 2) So you might prefer a traditional, embalmed, open-casket funeral and burial - until you read about the process and the ultimate futility of it - eventually, "the worms crawl in, the worms crawl out," and...well, you know the rest of the song, or: 3) Cremation, and of course Roach includes a rather detailed description of the sequence of events that occur in a body subjected to extreme temperatures necessary to turn a sac of water into a pile of ashes.

Still, all in all, I think I prefer the cremation route. I may be OK with donating organs to save other people, but I don't want my body lying around being poked, prodded, dissected, getting a face lift, or otherwise experimented on.

Dipping My Feet Into The Case Study Waters

The Hot Tub Mystery

SUNY Buffalo has developed a library of case studies for use in science teaching. Many are geared toward college biology classes, but some can be adapted or are already more or less appropriate for regent -level biology.

I've wanted to play around with case studies for a while but haven't had the time or mental energy to invest. So a couple of weeks ago I found one that doesn't seem to require a lot of planning and is pretty straight forward and relevant to the human body/homeostasis unit we are working on. The really nice thing about it is how it brings together the workings of the circulatory, nervous, endocrine, and excretory systems to understand the cause of death in a couple who are found dead in a hot tub.

The task for students as outlined in the case study is to take on the role of the detective who investigated the case and write a final report on the cause of death. In my high school classes I'm sticking with that task, but I'll give them some options for presenting the report in the form of powerpoint, a poster, etc. I won't have a lot of class time to spend on that part of the study. My 8th graders, who have a good deal more class time than the high schoolers due to the fact that they attend school during regents weeks and so on, will have a bit more freedom to produce something more creative - one group is already working on a film that will re-enact the accident.

The case study website provides a lot of information, at times too much information, about how to incorporate case studies into your teaching. The worksheets have questions attached and are available in PDF or easy printing. The basic flow of my approach is as follows:

1. We've already learned about the circulatory system through "traditional" means, and have discussed homeostasis throughout the year.

2. I introduced the case, which is broken down into 3 segments. I started with part one, where students are given some very basic background information and the facts of the case as reported by two detectives and a maid who discovered the bodies.

3. Students research some questions that are fairly easy to grasp, such as the effects of alcohol on the body, what the drug lasix is used for, how the body responds to high temperatures, etc.

4. I teach through traditional means the nervous system, highlighting along the way the parts that are particularly relevant to the case study.

5. Students get part 2 of the case study and learn more information about the case that underlines the importance of understanding how the nervous system regulates homeostasis and how the hot tub, alcohol, and lasix combine to disrupt that regulation. The subject of kidney function and hormones comes up.

6. Teach endocrine and excretory systems.

7. Students compose final reports.

Along the way students are given opportunities to work in small groups sharing information and discussing the details of the case. We are not told if the autopsy indicates drowning as the cause of death, so there may be disagreements over whether they died and then slipped under the water or whether they lost consciousness and drowned. Then the question of why this would happen to both, seemingly at the same time.

Oh, "PS" or whatever - There are teacher notes available for the case studies but you have to be registered and recognized as a legitimate teacher - a fairly painless procedure if your name appears on your school website as a member of the faculty. It does take a day or two for the elves to process your application.