Leaf Color and Inquiry

Leaf color

As many of you know, I am in upstate New York this summer and fall. I’m simply amazed that fall is progressing so fast. This photo were taken back on Aug. 24th. Leaf color as a topic for inquiry has a great deal of potential. Nearly everyone living in the Northern temperate areas, at one time or another, has marveled at the brilliant foliage displays and asked the question: “Why do leaves turn color?”

Carl Zimmer, author, blogger from Science Blogs and science writer for the NY Times is also fascinated by leaves. Carl has a 4 year series of articles that explore the ongoing research into why leaves turn color in the fall. This is a great place to begin an investigation into how science works in a way that is very accessible to students (and teachers).

Carl does a great job of summarizing the pace and direction of the leaf color research in an article that appeared in the NY Times and in the following blog posts: 2007, 2006, 2005, 2004,and 2003.

Carl’s excellent articles refer directly to the original papers–many of them available online. Because of the intrinsic interest in this phenomenon, I think you’ll find these papers very accessible to you and your students with Carl’s introduction.

An additional resource that you are going to want to check out is at the Harvard Forest website. There you’ll find a very comprehensive resource about the biology of Autumn Leaf Color as well as links to the pdf’s of many of the relevant research papers.

I hope to find time to dissect the questions that are asked in these articles and how you might want to do some investigating on your own in future postings. Consider reading these articles as you explore the woods this fall and let your own mind wander and find new questions about leaf color that you and your kids might try to answer.


Cornell Institute for Biology Teachers Resources


As you prepare for this year, consider adding at least one involved laboratory experience for you and your students to your curriculum. The web is full of excellent resources for you. The CIBT labsfrom Cornell’s HHMI program are just one example.

Several years ago, Kylee Sharp shared a presentation at a KABT gathering (may have been KATS) about the “Goldenrod Lab” she had learned about at an NABT convention. She had a printed resource that she really would have like to have distributed but she didn’t feel that she could because it was copyrighted and she didn’t have permission. That resource was from the Cornell Institute for Biology Teachers–A long-time HHMI funded program that has done a great deal over the years to provide resources to help biology teachers to their job, better. Well, the CIBT has now made all of their printed lab resources available online and Kylee can now share this lab with others with a clear conscience.

Check out these labs, there are 32 different labs that deeply involve the student and teacher in inquiry, are well tested, and cover a diversity of biology topics. The web site is not the easiest to navigate so here are the categories of labs with links to the labs in that category. You’ll need a pdf viewer to access the labs.

    Chemistry for Biology
    Ecology and Evolution
    Everyday Biology
    Molecular Biology
    Reproduction & Development


Global Warming: An Introduction to the Research and the Nature of Science

Since November, 2006, I have been enjoying a series in Natural History Magazine entitled “Samplings: The Warming Earth”. (scroll down the page to find the “Samplings” specific to “The Warming Earth.”) The articles are actually very concise summaries of research published in professional journals. The samplings are representative of a wide range of research. For example, there are summaries of research that predict possible effects of climate change (as “Pipefish Baby Boom”) to identification of contributing factors (“Don’t Blame the Sun”), to how climate change may be tracked (“Reading the Leaves”). Here’s a sample from one of this month’s (May 2007) “Samplings:”

Oysters on the half shell are considered a delicacy, but what about mussels on the three-quarter shell? A new study shows that human emissions of carbon dioxide (CO2) could reduce bivalves’ ability to build their shells by as much as 25 percent.
In addition to warming the Earth, excessive CO2 is making the oceans more acidic, which decreases the concentration of dissolved carbonate in seawater. Without carbonate for building their shells, numerous minute organisms—including corals and species of phytoplankton and zooplankton—are showing alarming signs of distress. Now Frédéric Gazeau, a marine biologist at the Netherlands Institute of Ecology in Yerseke, and several colleagues have shown that the phenomenon propagates up the food chain.
In the laboratory, Gazeau exposed mussels and oysters to water with various levels of CO2 for periods of two hours, measuring the water’s average pH and the change in its alkalinity, which is proportional to its concentration of carbonate. From alkalinity levels he calculated the mollusks’ rate of shell construction, or calcification. Sure enough, the higher the water’s CO2 concentration and the lower its pH, the slower the mollusks’ calcification.
If atmospheric CO2 reaches the levels expected by 2100, Gazeau predicts the calcification of oyster shells could decline by 10 percent and that of mussel shells by a quarter. As the declines in calcification affect the development of juvenile shellfish, and as adults become more vulnerable to predation, both aquaculture and marine ecosystems are likely to change. Gazeau stresses that his findings are preliminary; he measured only short-term responses to high CO2 and low pH. But his next experiment will test their responses over several months. (Gazeau, F., C. Quiblier, J. M. Jansen, J. Gattuso, J. J. Middelburg, and C. H. R. Heip [2007], “Impact of elevated CO2 on shellfish calcification,” Geophysical Research Letters 34, L07603, doi:10.1029/2006GL028554)

Links: Netherlands Institute of Ecology (NIOO)
Laboratoire d’Océographie de Villefranche (LOV)

—Rebecca Kessler

Recently in class a student commented that he didn’t “believe” in global warming. When asked why, he responded that he didn’t see how scientists could study such a phenomenon. This student comment followed upon the heels of a conversation with a colleague in which we lamented the difficulty of providing students with insights into the nature of science. It occurred to me that perhaps the Natural History “Samplings” might be a way in which I could simultaneously introduce my students to some of the research on global warming and provide insights into “how scientists know what they know”.

This turned out to be a very simple, but effective assignment. My students were asked to read a specific number of summaries (depending on the grade they wanted to earn). For each article they selected to read they needed to identify three components: the research question or problem; the kind of data collected and/or an explanation of how the data was collected (through field experiment, computer modeling, etc); and the conclusion of the research. After reading as many summaries as they committed themselves to, they were asked to write a reflective summary in which they explained what they learned about global warming or about how scientists work.

Based on what my students wrote (9th grade biology) and on a follow-up class discussion, I found this simple assignment to be successful. In addition, it had the benefit of piquing their interest in global warming!

Sandy Collins
Biology (9th grade)
West Junior High School
Lawrence, KS 66044


I’m posting this info for Randy who is unable to attend and present at the 2007 KATS KAMP KABT thread. Randy was going to share a number of resources that he has tried out and found effective in his biotech courses and in AP Biology that deal with microarrays. These include:

Web animations such as this one from Malcolm Campbell at Davidson (click on the screen shot):

Microarray animation

Virtual Labs like this one from the Genetic Science Learning Center in Utah (click on the screen shot):

Virtual Lab

Select the BEOP link for teaching materials. (Student materials and answers)

BEOP Microarray paper by Carolyn A. Zanta, UIUC-HHMI Biotechnology Education and Outreach Program (BEOP)

And finally two papers:

Microarrays made simple: “DNA chips” paper activity, by Betsy Barnard from the online component of the American Biology Teacher, March, 2006. You’ll need to be an NABT member to access this link.

DNA Microarray Wet Lab Simulation Brings Genomics into the High School Curriculum, A. Malcolm Campbell, Carolyn A. Zanta, Laurie, J. Heyer, Ben Kittinger, Katleen M. Babric and Leslie Adler, CBE–Life Science Education, vol. 5, 332-339, Winter 2006


Analogies in Biology teaching

One of the essential tools in a biology teacher’s tool kit is the analogy. Analogies help students to form their own, personal biological concepts within a more familiar context. Analogies are truly a double-edged sword, (using an analogy to describe the use of analogy.) On one hand they help students to acquire and build their knowledge and understanding but on the other hand they invariably lead to the acquisition of some level of misconception. This negative aspect of analogy is particularly true when working with students just beginning their journeys (another analogy.) Teaching with analogies is a balancing affair. A teacher needs to present the analogy to begin the discussion but also follow up with a discussion of the limits of the analogy.

For a teacher just finding a starting analogy can be a challenge. Here’s two:

Today, I came across a great analogy describing the mechanism of cell receptors and flu viral infection at Effect Measure blog.

Earlier I came across one of the better analogies I’ve seen for describing the developmental toolkit at PZ Meyer’s Pharyngula blog.