Those of us born after World War II have take antibiotics for granted. Strep throat? Ear infection? Acne? Bronchitis? Not a problem. Take the full prescribed antibiotic dose and you are cured. The reality of antibiotic resistant bacteria however, disrupts that scenario. No longer can we always trust in a full recovery from a bacterial infection after completing the antibiotic regimen. Rather than continuing to create new and different antibiotics, the trend in research is to discover the mechanisms of the antibiotic resistance in order to neutralize it.

How Some Bacteria Survive Antibiotics from ScienceDailydescribes how researchers at the University of Illinois, Chicago, studied bacterial action in the presence of erythromycin and related antibiotics. These drugs incapacitate the bacterial protein factories, ribosomes. All cells have ribosomes which are the site of translation in protein synthesis. Erythromycin prevents newly synthesized proteins from detaching from the two subunits of the ribosome, thus preventing the bacteria from thriving. The researchers discovered, however, that these drugs can signal the bacteria to switch a bacterial gene on that enables bacterial release of newly synthesized proteins from the ribosomes. Thus, they effectively resist the drug in a process known as inducible antibiotic expression.

The article quotes one of the researchers

Combining biochemical data with the knowledge of the structure of the ribosome tunnel, we were able to identify some of the key molecular players involved in the induction mechanism. . . .We only researched response to erythromycin-like drugs because the majority of the genetics were already known. There may be other antibiotics and resistance genes in pathogenic bacteria regulated by this same mechanism. This is just the beginning.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

A manifestation of evolution, antibiotic resistance aligns with the Life Science standard of The National Science Education Standards, “Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.” Also related is the structure and function section of the standard: prokaryotic cell structure, the ribosome, and protein synthesis.

Ask students if they have ever had an ear infection or strep throat. What did they do about it? Lead them to disclose that they went to the doctor, were prescribed an antibiotic and took it for the full course, often 10 days. Ask if they were cured then, or did anyone suffer a recurrence within the next week or so? If yes, why? Then what did they do? Lead them to articulate the concept of bacterial resistance. Consider showing visuals of a typical animal eukaryotic cell side by side with a bacterial cell. This will highlight the size and structural difference, and enable student comprehension of how bacterial cells can colonize a eukaryotic cell. Showing this image and eliminating the text or modifying it to inform students that the red shows a liver cell, while all the green spots are bacteria cells could do the trick. Make sure they understand the activity of the millions of bacteria cells a) consumes nutrients needed by one’s own healthy cells and b) produces waste that makes one sick.

If you’ve already discussed the characteristics of living things, cell theory and cell structure, lead students to recall the importance of ribosomes to all living cells. Ask, what might happen if the function of the ribosomes were disrupted? Students should reason that protein production would stop and the cell would die for lack of needed proteins. Inform them that this is the way some antibiotics work; they interfere with the bacterial cells’ ribosome function. (Prokaryotic and eukaryotic ribosome structure varies slightly allowing the eukaryotic ribosomes to remain unaffected.) Ask, what if the presence of the antibiotic signaled the bacteria to produce a protein (turn a gene on) that interfered with the drug’s ability to disrupt the ribosome’s work? Allow plenty of wait time for them to think this through logically. They should arrive at the idea of antibiotic resistance, even if they don’t use that phrase.

Allow students to read the first three paragraphs above and follow the links. The protein synthesis link however, is probably too advanced for middle school students and can be eliminated. Have them read the article How Some Bacteria Survive Antibiotics. Assess: what is an antibiotic? How do drugs like erythromycin work? What is inducible antibiotic expression? How might it be helpful to know the mechanisms by which bacteria resist antibiotics? Describe how antibiotic resistance is an example of evolution.

Here are some additional resources from the National Science Digital Library Middle School Portal related to antibiotic resistance and bacteria: Introduction to Bacteria; Microbes: Too Smart for Antibiotics?; Microbes: What They do and how Antibiotics Change Them; Evolution : Online Lessons for Students: Activity 1; and What’s making you sick?

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We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

Typically, a middle school life science study of cells explores the ways cells get what they need and get rid of waste, and the cell cycle concept, including how cells reproduce through mitosis. Discussion of cancer at this time is appropriate since cancer cells share the needs of normal cells in terms of obtaining nutrients and getting rid of waste. However, they differ in their cell cycle. Cancer cells lack an interphase–meaning they are in a near constant state of reproducing with little down time in-between divisions. This leads to the formation of a mass of undifferentiated cells, a tumor.

Angiogenesis is the tumor’s ability to construct blood vessels that become the circulatory system for the tumor. Thus, needed oxygen and nutrients are effectively delivered and waste is removed, allowing the tumor to thrive. These blood vessels are also potential blood-letting points, increasing the risks of surgical removal. If angiogenesis is curtailed, the tumor is deprived and fails to thrive reducing potential surgical complications.

On April 19, 2008, ScienceDaily reported that a team of researchers in Australia has identified a master gene responsible for angiogenesis. The gene is named RGS5. The team was able to remove the gene from experimental tumor cells, and this caused angiogenesis to reverse itself! This means that oncologists may have another tool to treat cancers in more targeted ways; ways that do not affect healthy cells, only cancerous cells.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

Ask students what cells need to thrive. Their list should be consistent with what all living things need: ability to take in nutrients and get rid of waste, to manufacture needed materials and break down no longer needed materials, and to reproduce. It might be appropriate at this time to show them a schematic of the cell cycle. What are student conceptions of cancer and tumors? Ask if they think cancer cells have different needs than those already discussed? Why or why not?

What is a tumor? How might it differ from or be the same as other organs in the body? A tumor is a mass of undifferentiated cells as opposed to cooperative tissues organized in a functional organ. And it is not part of a functional organ system except in the sense that the tumor’s blood vessels are derived from the healthy organ system’s blood vessels: cells come from other cells.

Lead students to conclude that cancer cells are like other cells with respect to the cell cycle and needs. Then ask, so how is it that cancer cells can grow into a tumor while healthy cells do not? Lead students to the one difference in the cancer cell cycle as compared to healthy cells’ cycle: lack of interphase. The lack of interphase may be attributed to a genetic mutation that fails to produce the needed proteins that signal interphase, or an environmental factor that prevents detection of the interphase signal.

At this point, you have raised student awareness of the nature of cancer cells and tumors. The students are now ready to hypothesize ways to interfere with tumor growth. Solicit and accept all reasonable hypotheses. Ask what if there was a way to control/eliminate a tumor’s ability to construct blood vessels? What do you predict the outcomes might be? Why? What leads you to believe that is a reasonable prediction? Make sure students use known facts about cell structure and function to support their predictions.

Have students read the article: World-first Discovery Could Help Treat Life-threatening Tumors. What other questions come to mind, questions which there are no pat answers to at this time? For example, does RGS5 also control blood vessel formation in healthy tissue and organs? How can it be controlled to impact only tumor blood vessels? What other investigations are needed in order to learn how to use this science knowledge, to apply it to a technological innovation to treat cancer?

The lesson described connects to both the Life Science and the Science as Inquiry content standards of the National Science Education Standards. Here are some additional resources from the National Science Digital Library Middle School Portal related to gene function, cells, and cancer: The Genetic Science Learning Center: The Basics and Beyond; Cell Differentiation; Lessons on Cells, Tissues ,and Organs; and Science sampler: Cancer-Mitosis Run Amok.

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We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

This week’s blog focuses on Earth Day, April 22. There is no news article accompanying today’s blog. Instead, we provide you with an assortment of resources related to Earth Day. Do you know how Earth Day started? You can find the answer to that question and more in The History of Earth Day by Gaylord Nelson. For instance, it might surprise your students to learn that there has not always been an Earth Day. The first Earth Day occurred in 1970.

Your own perception of Earth Day might need some updating too. It’s no longer just about being aware of what stresses our environment, refraining from littering and picking up trash, or planting a tree. There now exists, for example, a Green Schools initiative consisting of four programs: healthy foods, curriculum, policy and civics, and green facilities. Consider how you and your students might get involved with one of these programs in order to promote environmentally friendly schools.

EarthDay.gov is a treasure-trove for the classroom teacher. Scroll down the page for a list of linked topics, including acid rain, climate change, drinking water, endangered species, estuaries, ground water, invasive species, National Youth Service Day (April 20-22), and trash: reduce, reuse, recycle.

Want to know what Earth Day-related events are occurring near you? You can enter search terms or search by date or location at http://ww2.earthday.net/search/node.

Here are some additional resources from the National Science Digital Library Middle School Portal related to Earth Day and environmental education: Science Themed Days and Weeks; Why Earth Science?; Global Learning and Observations to Benefit the Environment (GLOBE); and AAAS Atlas of Population and Environment.

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

Many middle school curricula include attention to ancient American people and their cultures. This blog entry may be helpful in making connections to the nature of science and scientific enterprises as part of an integrated approach in studying the Anasazi or ancient Peublos. The story titled “Vanished: A Pueblo Mystery,” published in the New York Times,April 8, 2008, enlightens readers regarding the science of archaeology.

Archaeologists rely on empirical evidence to reconstruct past events. However, this empirical evidence does not normally emanate from controlled laboratory experiments, conceived of and performed at the scientists’ will. Rather, archaeologists use evidence left by the activities of not only people that lived long ago but other organisms as well. They must be skilled observers.

The graphic accompanying the article shows where the Anasazi migrated from–what is now southwestern Colorado–and where they migrated to–what is now the Davis Ranch and Tucson, Arizona, area. There is also a slide show of images of dwellings among other relevant artifacts. For archaeologists interested in this part of the world and these people, the article states, “the most vexing and persistent question in Southwestern archaeology [is]: Why, in the late 13th century, did thousands of Anasazi abandon Kayenta, Mesa Verde and the other magnificent settlements of the Colorado Plateau and move south into Arizona and New Mexico?”

This is not the first time this question has been asked or that an answer has been proposed based on evidence. For example, drought has been documented during this time, providing a seemingly good explanation for the migration. However, evidence suggests many people were able to survive the drought. That fact casts doubt on drought as the only cause for the migration. Further, the area the Anasazi migrated to was actually drier than that which they migrated from.

An alternate hypothesis is based on the pollen record. “Measurements of the thickness of pollen layers, accumulating over decades on the bottom of lakes and bogs, suggest that growing seasons were becoming shorter.” Even this fact in combination with the relatively short drought does not convince many archaeologists these were the reasons for the migration. Why did the Anasazi never return, even when the drought ended? Evidence suggests they did not leave in a hurry, but planned their exit as if they intended to return.

Even more interesting hypotheses are presented regarding the role of religion in the migration. Donna Glowacki, an archaeologist at the University of Notre Dame, cites evidence that suggests the early culture of the group, prior to the migration, included a tradition where only a select, privileged few had access to the largest, most well-equipped dwellings. She asserts a change can be detected after the migration in the southern villages. There evidence indicates fewer of these select kivas are found, suggesting there was less reverence for a select few. The article indicates this change could be analogous to the Protestant reformation.

So who’s right? Well, no one knows for sure, but the Village Ecodynamics Project is set to bring together these various hypotheses to see if a coherent, though probably somewhat complex explanation, or theory, can be constructed. The researchers will use evidence of “rainfall, temperature, soil productivity, human metabolic needs and diet, gleaned from an analysis of trash heaps and human waste” to reconstruct events and come to conclusions.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The article illustrates well the nature of science. Our understanding of the Anasazi migration is undergoing revision in light of new evidence and reinterpretation of existing evidence from new perspectives. It calls attention to the various scientists working on the same project, each contributing unique expertise and building new knowledge. The article conveys several possible hypotheses, all of which need to be thoroughly investigated to see if any can be discarded. It underscores that scientists don’t have definitive, pat answers, only best guesses based on reasonable interpretations of much evidence. Several kinds of, or sources of, evidence are identified giving readers an indication of the nature of archaeology in particular.

Ask students to describe archaeology. Affirm their responses and ask them to elaborate as much as they can. They should use terms like ancient, culture, science, observation, inference and reconstruct. Ask students what kind of knowledge or skills a good archaeologist needs. They should include knowledge of anatomy, plants, and history, and excellent observational skills. Archaeologists need to be global thinkers, able to see relationships among seemingly disparate observations. They should be good team players. If needed, ask leading questions such as: What other fields of science might be related to archaeology? They should include botany, zoology, and anthropology even if they don’t use those names for them.

Explicit connections to life science and earth science can be made, particularly to botany and climate. Ask students how knowledge of the growing season can be inferred from the pollen record. How can inferences regarding wet or dry years be obtained from tree rings?

Here are some additional resources from the National Science Digital Library Middle School Portal related to the nature of science and fields of science: Science Sampler: Jumping to the Right Conclusions, Inferences and Predictions; Presenting a Logical and Reasonable Case Using Logical and Reasonable Arguments; Frequently Asked Questions: Questions about Paleontology.

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

This week’s post focuses on the definition of species and its implications beyond science content knowledge—specifically, how the definition is related to species conservation and protection.

For example, the brown bear of the Iberian Peninsula is a different species compared with other European brown bears because it is geographically isolated, right? According to a press release, New Study Changes Conditions for Spanish Brown Bears, published by AAAS’s EurekAlert! there are just two small populations of this bear and they are threatened. One idea to help bolster their population size is to introduce brown bears from other European populations. However, this may cause hybridization and eventual loss of the Iberian Peninsula brown bear species. Further, what makes conservation biologists think the two different bears will interbreed successfully?

According to the Life Science content standard of the National Science Education Standards, middle school students should be learning concepts associated with structure and function in living systems; reproduction and heredity; regulation and behavior; populations and ecosystems; diversity and adaptations of organisms. All of these areas of study are related to the concept of species. That is, discussions in any of these areas will necessarily be founded on an understanding of the term “species.”

Can we take for granted that middle school students have developed an accurate concept of species on their own, through personal experience? Because they can distinguish cat from dog, a rose from a maple tree, and a human from an ant, is it safe to assume they have a good grasp of the concept? Not if we wish to facilitate and broaden students’ conceptual understandings to progressively more sophisticated levels.

Students understand that cats and dogs, roses and maple trees, and humans and ants do not interbreed. Thus, they have an understanding of the biological definition of species. But things can get complicated and this definition does not always fit. Another perspective assumes reproductive isolation defines species. That is, if two populations are physically or temporally isolated preventing interbreeding, then they are considered separate species. That works well conceptually for most middle school students’ experience, but what about when individuals from one geographically isolated population are introduced to another, either intentionally or unintentionally, and they successfully interbreed?

When discussions around Mendelian genetics occur, the concept of hybrid is introduced. Plants do this all the time. Is the hybrid a new species? They often can and do interbreed. Are the offspring a new species? Most would hesitate to say yes. Then do we revise our definition of species? Those reproductively isolated populations really are the same species after all?

Contrary to what most people believe, the concept of species seems to be a moving target in terms of pinning a definition on it. As such, it is open to criticism from people who believe science is supposed to be definitive. This presents an opportunity for teachers to reinforce the nature of science, and life science particularly. Living systems, from a single cell to a biome, are dynamic and not entirely definitively understood. (If they were, conservation would probably not be an issue!)

Assuming a fixed definition of species may be unreasonable. One’s definition of species is contextual, dependent upon the current issue under consideration. It is important that discussants have a common definition of species in these instances. Why? Because the focus of and outcomes of species-related discussions can determine political policy, such as what gets listed as a threatened or endangered species and receives federal funding for protection from habitat destruction or hunting.

DNA sequencing allows for almost unequivocal determination of whether individuals from two different populations are the same species, and consequently subject to the same political treatment. In the case of the Spanish brown bears, DNA sequencing suggests they are not a distinct species from other European brown bears. That means introducing bears from other populations will not supplant the Iberian Peninsula brown bears. The proposed conservation strategy is a viable one. Scientists are confident that the introduced bears will successfully interbreed with the Spanish brown bears due to the genetic similarity. This constitutes a prediction, and its accuracy will be determined only after bears are introduced into the area.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

Consider the American Bald Eagle. It is cited as a success story of the Endangered Species Act (ESA). It has recovered from its endangered status and was delisted in 2007. This means the bird is no longer protected under federal law in terms of some kinds of hunting and habitat protection. States are free to make their own regulations regarding hunting and protection of the species.

More recently, the Northern Rocky Mountain population of gray wolf is being delisted. Last year, the Western Great Lakes grey wolf population was delisted. States that are host to these two populations have the power to regulate hunting and management of the animals. However, any wolves on National Park Service land or outside the two areas mentioned above, are under federal government protection.

How is species defined? Ask students if dogs and wolves are separate species. How do they know? Accept all reasonable responses. Are lions and tigers? Are saber toothed cats and Bengal tigers? Lead students to define species in terms of (a) macroscopic anatomy, (b) geographic isolation (lions and tigers), and (c) temporal isolation (extinct and extant cats). This discussion should highlight the difficulty in pinpointing a definition. None is incorrect, yet none is fully sufficient. This is acceptable in classroom discussions, but when conservation groups discuss species, they have to be specific. For example, in delisting the Rocky Mountain gray wolf, the documents specify the geographic region that defines the population. Individual animals falling outside the defined geographic range are not delisted and remain protected by the ESA.

Can students imagine that features other than those immediately visible could be considered in determining who is different and who is the same species? For example, in Batesian mimicry two species are physically similar, but one is poisonous to predators while the other is not. Lead students to understand that there are microscopic or chemical means of determining similarity and differences. Conversely, two populations can appear to be quite different but are chemically quite similar. (This may explain the original assumption that the Spanish brown bear was a separate species from other European brown bears.) The morphological difference is attributed to environmental influences, not genetic differences, and so it is predicted the two populations could interbreed successfully. That’s often good news for conservation management.

What do students think the Endangered Species Act is? Why is it needed? Allow them to brainstorm. Then show them pages from http://www.fws.gov/endangered/whatwedo.html to either confirm their list or amend it. Can they name any organisms on the list now? Call attention to species other than mammals, including plants. How do students suppose an organism gets listed/delisted? Have students investigate this question at http://www.fws.gov/endangered/listing/index.html. Facilitate student discovery that the process is not neat and easy necessarily. Rather it can be emotional and partisan. Why?

Here are some additional resources from the National Science Digital Library Middle School Portal related to conservation and wildlife management: US Fish and Wildlife Service; Natural Resources, the Environment, and Ecosystems; and DDT Quest.

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

This week’s blog draws from several news sources—washingtonpost.com, The New York Times, Science News Online and Science Friday. All these sources have stories and photos related to a study published March 7, 2008, in Science by researchers Victor Polyak and Carol Hill. (Science Friday features a 15-minute audio clip of an interview with Polyak.) The research suggests that the Grand Canyon began forming 17 million years ago. However, for the past 100 years or so, geologists have agreed, based on a robust data corpus, that the Grand Canyon is probably five to six million years old, even though the rock from which it is carved is up to two billion years old. So what have Polyak and Hill done to upset this long-held theory of the Grand Canyon’s age?

To put it simply, they gathered new data and analyzed it using new technology. That is, they gathered rock samples called mammillaries from caves. These mammillaries are associated with ancient water tables and suggest previous levels of the water table. Polyak and Hill then analyzed these samples with improved rock-dating technology involving the radioactive decay of uranium to lead.

The Science News Online article describes the researchers’ findings as follows: The Grand Canyon began forming 17 million years ago at the western end in a west to east direction, and at a rather slow rate. Some time later, the east end of the Grand Canyon began forming from east to west, at a much more rapid rate. Eventually the two ends merged and the Colorado River emerged.

However, some scientists suggest Polyak and Hill’s methods and interpretations may be too narrow or incomplete. For example, their assumption that all the mammillaries examined originated in an ancient water table may not be a safe one. One critic noted that springs do occasionally emerge from the canyon walls and they could produce mammillaries as well. Another point of contention deals with the lack of 17-million-year-old sediment, which would be evidence of a 17-million-year-old river. Hill counterargues that such sediment may not exist because the scale of the hypothesized 17 million-year-old, western river system would not produce sizable amounts of sediment. In addition, river erosion tends to destroy such potential evidence.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

Estimating the age of the Grand Canyon is related to the History and Nature of Science, Science as Inquiry, and the Earth and Space Science content standards of the National Science Education Standards. With respect to the first two standards, several themes emerge. The researchers proposed using improved laboratory techniques and new data sources to make an estimate of the age of the Grand Canyon. In this way, they demonstrated the idea that science advances with new technologies. Science also seeks disconfirming evidence to existing theories as a means of gaining increased certainty regarding what we know about the natural world. If scientists fail in their attempt to find disconfirming evidence, they have succeeded in strengthening the existing theory. If they find disconfirming evidence of existing theories, then they pave the way to new lines of research, which must be further investigated. Eventually, existing theories may be either supplanted or revised in light of the new evidence, or they may be strengthened should the new evidence turn out to be unreliable or invalid.

The news sources related to this research also provide “air time” for scientists who argue alternate interpretations of Polyak and Hill’s data and who point out that Polyak and Hill may be ignoring some facts that impact their conclusion. These presentations underscore the role of argumentation and evidence based logic in advancing scientific knowledge as well as the social nature of science.

Ask your students if they know how old the Grand Canyon is. Ask them if they imagine someone knows, even if they don’t. From here, the discussion is going to go in one of two directions: (1) If they imagine someone knows, how do students imagine the someone knows how old the Grand Canyon is; what kind of evidence might have been used? Entertain all student contributions and stipulate that the students provide some justification for their response. You may need to do quite a bit of guiding and scaffolding here to lead students to support only evidence-based and logical responses. (2) If students imagine no one really knows, ask why not; what prevents human beings from knowing?

Depending on your students’ background knowledge and context you can relate the discussion to a variety of instructional goals and learning objectives. Do you want to emphasize the nature of science, evidence-based argumentation, and the social aspects of doing science? Then choose excerpts from Science Friday’s interview, which highlight these aspects in the context of real scientists doing real science and devise discussion questions for your students to reflect upon in order to increase their awareness of the nature of science.

Maybe you want to highlight some methods of science like rock dating. Perhaps you can use this opportunity to illustrate how new questions can emerge from gathering evidence intended to answer another question, as is illustrated in the final paragraph of the washintonpost.com story.

Or maybe you want to give students practice with science literacy. Put students in small groups and give each group one of the four sources listed in the first paragraph of this blog. Devise two or three open-ended questions for each group to discuss and reach consensus. Have the students jigsaw into new groups and share the consensus of their first group. How does each student now understand the issue of determining the age of the Grand Canyon? How does this issue intersect with the bigger idea of the nature of science?

Here are some additional resources from the National Science Digital Library Middle School Portal related to rock dating, earth systems structure, and teaching the nature of science: Date a Rock; Geologic Time: The History of the Earth; Observe River Erosion Creating Waterfalls and Chasms; Ready, Set, Science! Making Thinking Visible: Talk and Argument, chapter 5.

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

Seed gene banks exist throughout the world. As you might guess, their purpose is to catalog, store, and protect as many varieties of plants as possible. These banks are useful to plant breeders trying to find crop species that are more drought or disease resistant, for example. They also provide a resource for countries in recovery after natural or man-made catastrophes. For example, after the tsunami in Malaysia in 2004, rice growers were able to obtain salt-tolerant varieties of rice not normally gown in that area. However, many seed banks are located in areas of the world where they are susceptible to destruction. Seed banks in Afghanistan and Iraq have been ransacked.

A consortium of organizations has collaborated in order to address this problem and provide a centralized, stable, reliable site for preserving and protecting world crop seeds. On February 28, 2008, the Svalbard Global Seed Vault began operating. The New York Times and ScienceDaily both reported the event. The Times article, Near Arctic, Seed Vault Is a Fort Knox of Food, is accompanied by numerous photographs and a map indicating the location of the vault. The ScienceDaily article, Thousands of Crop Varieties Depart For Arctic Seed Vault, contains one photograph and numerous links to related articles. Both articles describe the project, who is involved with the project, and why.

Did you know there are about 1,200 varieties of banana plants worldwide? Only about half have been preserved. Other food crops exhibit thousands of varieties as well. The Times notes that, in the United States, “eighty percent of maize types that existed in the 1930s are gone.” The rapid loss of crop plants on the planet heightens the need to preserve as many as possible at this time for their potential in serving future generations.

The Consultative Group on International Agricultural Research (CGIAR) maintains and coordinates seed gene banks around the world, encompassing 600,000 plant varieties. Its goal is to back up all known varieties of useful plant varieties in the Svalbard Global Seed Vault.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The National Science Education Standards are sometimes criticized for the lack of emphasis on plant biology. However, the Life Science Content Standard for grades 5-8 allows for elaboration on plant biology in many contexts. There are five big ideas within this content standard, none of which excludes plant biology: structure and function in living systems; reproduction and heredity; regulation and behavior; populations and ecosystems; diversity and adaptations of organisms. Teachers should strive to present instruction inclusive of all kinds of living things with respect to these five big ideas, including crop plants.

Entertain student estimates on the number of varieties of bananas, tomatoes, maize, beans, and so on. Present them with statistics reflecting the actual number of known varieties for the crops you choose. Ask what might differentiate one variety from another. Lead students to the idea of differences in optimal growing conditions and variety in tolerance with respect to things like drought, water quality, disease resistance, and yield. Ideally, you may be conducting an ongoing activity in which students grow, observe, and compare food crop varieties for some of these variables.

Can students think of any reasons to try and preserve this variety? Earlier posts to this blog have dealt with the topic of biodiversity. However, those posts centered on animal diversity. How important is it to preserve plant biodiversity? Why? Intended for educators, the article Plant Content in the National Science Education Standards lists several reasons for preserving plant biodiversity by virtue of the plant-derived products we depend on to maintain our lifestyle.

Students might recall the tsunami of 2004 or Hurricane Katrina. Ask them if crops that once thrived in those areas could be expected to thrive just as they did before the disasters. Lead them to the idea of salt residue left in soil. Drops of salt water on a paper towel allowed to dry will provide evidence to help students understand soil could be altered by salt water washing over it. Fresh celery or raw potato allowed to sit in salt water demonstrates the effect of salt on plants. Remind students of the Asian rice growers in the ScienceDaily article who found salt-resistant rice in the seed banks.

Imagine your students harvested 300 seeds from plants grown this year at school and you found a way to preserve them. One hundred years from now, students find those seeds and plant them in a natural setting. What do your students predict the outcomes would be? Will the seeds germinate? Will the plants thrive? Will they flower and produce seeds? What rationale do students provide to support their predictions? Lead them to understand the environment will most likely be altered from what it is now. There may be new pests, viruses, pathogens, and competitors. Tie the discussion to natural selection. Is it safe to assume that seeds preserved today can be planted 100 or 200 years from now with great confidence in their success? Then why preserve them? How should they be managed?

Recall the name “gene bank.” These banks can be conceived of as genetic repositories, not simply seed preservation sites. That means there is potential to isolate and manipulate useful genes from preserved seeds. Thus, it may not be necessary that the preserved seeds thrive but that they lend themselves to gene isolation. Periodic germination of preserved seeds followed by collection of new seeds may simulate the natural selection process and increase the probability that preserved seeds will thrive if germinated hundreds of years from now.

What about plants, such as bananas, whose seeds do not preserve well or are not reliable with respect to germination for various reasons. How can those plant species be preserved? There is no pat answer to this question; thus it is an excellent question for student inquiry. Students may propose things like cryogenics of tissues for later vegetative propagation or genomic sequencing for incorporation into some kind of surrogate seed embryo later.

Here are some additional resources from the National Science Digital Library Middle School Portal related to issues of plant biodiversity and plant breeding: Plant Biotechnology Basics; Agriculture Biotechnology FAQs; Thinking Green? Grow Your Own!

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

Talk of a looming recession and sky-high oil prices don’t seem to worry many Texans. Instead, they’re cashing in on the benefits of an alternative energy source, wind, literally.

Many Texans are happily trading defunct oil rigs for wind turbine installations on their land. One Texan is being paid $500 a month for each turbine he allows to be erected on his property. He currently has 78, with plans for 76 more.

According to an article in The New York Times on February 23, Move Over, Oil, There’s Money in Texas Wind, there are up to 4.5 million homes in America powered by wind. The top two states in wind-power production are Texas, with 4,356 megawatts, and California, with 2,439 megawatts produced in 2007. That might sound like a lot, but actually only about 1 percent of America’s electricity is wind generated. Industry experts predict it will top out at 5 to 7 percent. Some European countries, however, derive up to 20 percent of their electric power from wind turbines. It is European companies that are most actively developing wind power in the United States.

Wind generates electricity without the undesirable greenhouse gas emissions, and it is making many Texans wealthy. Is there a down side? Yes. It is still more expensive to produce wind-generated electricity than electricity from fossil fuels. The turbines are 20-stories high with blades as long as a football field. Wind-generated electricity is unreliable: no wind, no electricity. Wind is most abundant where the energy produced is least needed, necessitating transmission–something not fully available at this point. There are also aesthetic and

The news article is accompanied by a slide show and a graphic representation of the leading states in wind-energy production.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

From the National Science Education Standards, the motions and forces subtopic of the Physical Science Content Standard can be linked to this topic of energy. In addition, portions of the Science in Personal and Social Perspectives content standard are also related, such as populations, resources, and environments, and science and technology in society. Ask students what our primary source of energy is. Is that sustainable? What are some alternative sources? Once they identify wind, ask them: How does a wind turbine work? What are the pros and cons of wind-generated electricity? If you lived in Texas, how would you feel about wind farms? Why?

Share the news story with the students. Have any students changed their mind regarding how they feel about wind farms? Can they say why?

Here are some additional resources from the National Science Digital Library Middle School Portal related to issues of alternative energy, wind power, and science in personal and social perspectives: Wind Energy: Energy from Moving Air; Wind; Technology and the Environment: Alternative Energy; and the American Wind Energy Association Homepage.

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

What’s better than a day at the beach? A day at the beach and not being miserable for the next several days because of sunburn! That’s were the modern miracle of sunscreen comes into play. Did you know many sunscreens are products of nanotechnology? An advisory statement from the Australian Government’s Therapeutic Goods Administration, Safety of Sunscreens Containing Nanoparticles of Zinc Oxide or Titanium Dioxide, describes the properties of these sunscreens. One property is the familiar white color of these compounds, which can be made transparent by reducing the zinc oxide, or ZnO, particle size down to nanoparticles. However, this means the surface area ZnO particles is increased, and that means greater potential for chemical reaction with skin cell proteins, for example. Further, these nanoparticles may be more reactive to UV radiation.

On Monday, February 18, 2008, ABC Science Online posted a story, titled Tests on Sunscreen Nanoparticles ‘Reassuring,’ about research conducted in Australia. In the first study, researchers used a form of ZnO that contained a nonradioactive form of Zn, which differentiated it from all naturally occurring forms of Zn. This allowed the researchers to track whether the material was being absorbed by skin cells and transferred into the blood stream and excretory system. The researchers found “very little” ZnO was absorbed by the skin.

The second study included testing the toxicity of ZnO to immune cells. While the researchers found the ZnO to be quite harmful to the immune cells, they also found that high doses would be necessary and that the body would most likely eliminate the ZnO before damaging levels accumulated.

An ongoing study involves treating shaved mice with sunscreen containing ZnO nanoparticles and then testing their organs for ZnO levels. A future study is planned involving the impact of UV light on the toxicity level of the nanoparticles in sunscreen products used by lifeguards for a week.

An interesting aspect is that sunscreen formulations vary. It is possible that a given combination of compounds affects whether the nanoparticles are absorbed into the skin and to what degree they get metabolized. One of the researchers would have preferred to test commercially available sunscreens, rather than the generic type provided. He quotes an industry insider as saying “if you find something untoward about this then this could cause our products to be taken off the market plus could destroy the industry full stop.”

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The concepts of nanotechnology and properties of ZnO are related to the Physical Science content standard of the National Science Education Standards, which mentions that middle school students associate certain properties with specific materials. It also states that the sun’s energy “arrives as light with a range of wavelengths, consisting of visible light, infrared, and ultraviolet radiation.” Ask students why they should wear sunscreen. Ask if they know what elements or compounds might be in those lotions that protect them. What is the substance actually protecting them from? Lead them to the concept of the high energy UV rays which damage cells. Depending on your students’ background knowledge, you may want to mention that UV radiation works to denature some proteins and can cause DNA to mutate.

Ask students if skin cells are living. How do they know? Lead them to the idea that skin cells grow and reproduce, a characteristic of all living things. That means they take in substances and get rid of substances. The smaller the substance, the more likely it will be able to enter cells. What if the protective material in sunscreen, ZnO, was on a nano scale? Would you be concerned about using it on your skin? Why or why not?

Share the articles with your students. You could withhold the part discussing ongoing or future research studies and ask them: What do you think still needs to be investigated? How would you propose that be done? Lead them to design a “fair test” with the potential to yield meaningful results.

Here are some additional resources that are part of the NSDL Middle School Portal collection to facilitate your instruction regarding sunscreen, skin and UV radiation: What’s That Stuff? (scroll down and click on Sunscreen); Skin; Quick Take . . . on Sunshine, Rainbows and the Electromagnetic Spectrum; SPF 30: Exposing Your Students to Science

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.

Have you ever considered the irony of a gym full of people using electrically powered exercise machines to burn energy? What if the mechanical energy of those moving bodies could be converted into usable electric energy? That’s exactly what Arthur Kuo, a University of Michigan mechanical engineer, and his colleagues have done. Both News in Science and Science Friday focused on this story Friday, February 8, 2008.

The News in Science story, Knee Gadget Fires Up Your Mobile by Will Dunham, reports the device works like the electricity generators in hybrid automobiles, harnessing the heat normally dissipated from moving engine parts when the car idles. The knee gadget harnesses such heat during the phase when the foot is at the back of the stride coming away from the ground and moving forward to take another step with the help of knee flexor muscles. The video posted with the Science Friday story Harvesting Energy From Walking illustrates this nicely in slow motion segments. Color labels identify the key events in the process.

The device can power up to 10 mobile phones at a time, or other such small devices. However, due to its weight, 1.6 kilograms, or about 3 pounds, and its bulk, it’s not ready for the mass market yet. Both news sources report this is not the first device made to convert mechanical energy of the human body into electric energy, but it is the most promising thus far. Both stories show photos of the device on a knee.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

This story does triple duty in aligning with the National Science Education Standards of Physical Science, Life Science, and Science and Technology. It’s all about force and motion and energy transfer, as well as structure and function in living systems, and of course, abilities of technological design. You can start your discussion of this device and its related science concepts with the question posed at the start of this article. Lead students to articulate, review, and reinforce the notions of energy conversion and transfer in keeping with the law of conservation of energy. This provides a firm ground upon which the scientists hypothesize and predict. That is, the notion of the human body as a source of electrical energy is perfectly tenable due to the first law of thermodynamics.

Ask students, What is the by-product of all energy conversions? Can heat energy be converted to electric energy? How do you know? Have students read the Science Friday article and show them the video. Be prepared to replay the video a few times, in order to afford the students ample opportunity to process what it illustrates.

Here are some additional resources that are part of the NSDL Middle School Portalcollection to facilitate your instruction regarding energy sources and conversions: Energy Transfers; Quick Take on The Power of Electricity; and Quick Take on Energy Sources.

We Need Your Help

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? Do you have a favorite activity that you would like to share? We invite you to share with us and other readers by posting your comments. Please check back each week for our newest post or download the RSS feed for this blog. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School Portal science publications. Email us at msp@msteacher.org.