Crop Failures and Food Riots

In the spring of 2008, many news outlets reported that rice crop failures in East Asia could have been avoided. An infestation of the brown plant hopper is the cause for the crop failure. The science knowledge and biotechnology needed to breed resistant rice plants have been in existence for several years. However, funds were not available to mass produce these rice strains and get them into the hands of rice growers. This is one example of crop failure that, when combined with other agricultural woes, fueled food riots around the world, but especially among the poorest people in the least developed nations.

The New York Times published an article that comprehensively describes how this preventable tragedy happened – World’s Poor Pay Price as Crop Research Is Cut. As with most sociopolitical issues, a combination of circumstances over a long period of time must be considered if one is to accurately account for the current crisis. The article conveys the history of agriculture research, including the Green Revolution of the 1960s and the great advances that emerged then. Ironically that successful movement contributed to the current lack of available funding; as agriculture problems were solved and world food supplies outpaced demand, research money was directed elsewhere.

The article, part of a series on the world’s food production, includes a nice depth and breadth of information concerning agricultural research. Several photos and related links are included.

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

The issues described in the news article connect to the History and Nature of Science, Life Science, Science and Technology, and Science in Personal and Social Perspectives content standards of the National Science Education Standards. Here, we narrow our focus to the first two standards. However, this topic – world food supplies as related to agriculture and biotechnology – could easily serve as basis for an interdisciplinary unit in the middle grades.

Do any of the students have experience in growing vegetables? Ask students, what are some of the problems gardeners have to deal with in order to maintain their vegetables? What are some ways to deal with those problems? Help students to include the problem of insect pests in the discussion. Is it reasonable to assume that growers of crops on a large scale also have the same or similar problems? Can growers use the same approaches to deal with their problems that the gardener uses? Why or why not?

Ask students if they can identify one food plant, or crop, that is probably the world’s most common source of food. Consider keeping a list of all ideas and then asking the class to think carefully and critically when they answer these questions: What crop could probably be eliminated from the list, compared to the rest of the list? Why do they believe the food they are choosing to eliminate is probably not the world’s top food crop? You will hope that rice remains on the list!

Ask students to imagine that an insect has infested a large part of the world’s most important food crop. Consider putting the students in small groups in which they predict the consequences of an infestation. You might stipulate that they must have a clear prediction with logical justification for each domain: economy, culture, public health, government, military, and education. Next, ask them to articulate one or two questions that science could investigate in the hope of avoiding the consequences their group identified. For example, Which varieties of rice are most insect resistant? What other food crops can be grown in the areas where rice is currently grown? What nutritional substitutes should/could be distributed to areas where rice is in short supply? Students’ questions will vary widely and all are correct, as long as the questions can be subjected to scientific investigation and seem to point toward a solution to the stated problem.

Share with students the New York Times article, showing that such an event – insect infestation of an important crop – actually happened. Show them the pictures at the story’s web site. Inform them that the knowledge and technology necessary to prevent this disaster already exist. Ask students to speculate then on how this could have happened if people already know how to combat it. Lead them to understand the complexity of the history, funding, cultural values, and competition for funding as contributors to the situation. Finally, confirm and affirm the students’ predictions. They may have heard about food riots for example, in Africa and elsewhere. Ask them what direction they think governments and researchers should go next? Why?

As an extension, you could elaborate on the evolution aspect of the story: the way the bug has evolved through natural selection made possible by use of insecticides.

Here are additional resources from the National Science Digital Library Middle School Portal related to gardening, agriculture and natural selection: Thinking Green? Grow Your Own!; What Are Seed Banks and How Do They Work? and Dr. Saul’s Biology in Motion.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published May 21, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/19/12 by Jessica Fries-Gaither.

After 50 Years, Scientists Still Not Sure How DEET Works

DEET (short for N,N-diethyl-meta-toluamide) is the most widely used insect repellent in the world for a very good reason – it works really, really well! Just a quick spray on exposed skin keeps mosquitoes, flies, fleas, chiggers, and ticks away. Developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946, millions of people worldwide use DEET to ward off vector-borne diseases. First of all, why would researchers study DEET if it works so well? While DEET is an effective repellent, it doesn’t work against all bugs, it’s corrosive to plastics and there are concerns about its effect on human health.

 

Structural Formula for N, N-diethyl-meta-toluamide (DEET).
Courtesy of Wikipedia – Click on the image for a larger version.

How DEET actually works has puzzled scientists for more than 50 years. Scientists long surmised that DEET masks the smell of the host, or jams or corrupts the insect’s senses, interfering with its ability to locate a host. Mosquitoes and other blood-feeding insects find their hosts by body heat, skin odors, carbon dioxide (breath), or visual stimuli.

Amazingly, within a few months this year, scientists from two different labs have come up with competing explanations of how DEET works. In March of 2008, researchers at Rockefeller University in New York, said that DEET jams odorant receptors in insect nervous systems, in effect masking odors that would ordinarily attract the bugs. According to Dr. Leslie B. Vosshall, a researcher who worked on the project, now that they know that DEET targets OR83b co-receptors, they can quickly screen thousands of other compounds in hope of finding one that is even more effective and has fewer disadvantages.

Are you sure, ask researchers at the University of California, Davis? Mosquitoes flee because of their intense dislike for the smell of the chemical repellent and not because DEET jams their sense of smell. In August 2008, in a paper published in The Proceedings of the National Academy of Sciences, they provide a simpler explanation. Mosquitoes, they say, smell DEET directly and avoid it.

Dr. Vosshall, involved in the earlier study, said that her team stood by its work, and that its findings were based on a variety of experiments. So for now, the jury is still out.

Connecting to the National Science Education Standards

These competing explanations on how DEET works provides a perfect example of one aspect of the nature of science – Scientific Claims are Subject to Peer Review and Replication. Researchers in labs across the world work on answering many of the same questions. The results of their work are published in peer reviewed journals so that researchers around the world can examine their data and logic, identify alternative explanations, and replicate observations and experiments. Peer review is an integral part of genuine scientific enterprise and goes on continuously in all areas of science.

The National Science Education Standards in the History and Nature of Science Content Standard G describes what middle school students should understand about this part of the nature of science, including:

It is normal for scientists to differ with one another about the interpretation of the evidence or theory being considered.

Different scientists might publish conflicting experimental results or might draw different conclusions from the same data.

It is part of scientific inquiry to evaluate the results of scientific investigations, experiments, observations, theoretical models, and the explanations proposed by other scientists.

Although scientists may disagree about explanations of phenomena, about interpretations of data, or about the value of rival theories, they do agree that questioning, response to criticism, and open communication are integral to the process of science.

Additional Resources

Read the entire National Science Education Standards online for free or register to download the free PDF. The content standards are found in Chapter 6.

Science For All Americans Online: The Nature of Science
Science for All Americans consists of a set of recommendations on what understandings and ways of thinking are essential for all citizens in a world shaped by science and technology.

Household Product Database
List of products that contain DEET.

Chemical Technical Summary for Public Health and Public Safety Professionals
The Department of Health and Human Services provides a summary of all medical cases and research done on DEET.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Kimberly Lightle and published August 26, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/19/12 by Jessica Fries-Gaither.

What Are Seed Gene Banks and How Do They Work?

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? 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 Middle School Portal 2 related to issues of plant biodiversity and plant breeding: Thinking Green? Grow Your Own! and Seeds of the World: Journey to Forever.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published March 7, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 3/27/12 by Jessica Fries-Gaither.

June 8 Is World Oceans Day

World Oceans Day will be observed on June 8. Events are planned across the United States in coastal and inland locations, often aquariums. You can find a list of events and add your own to the World Oceans Day web site. The web site also gives suggestions for local events to increase awareness of the importance of the health of the oceans. The concept for a “World Ocean Day” was first proposed in 1992 by Canada at the Earth Summit in Rio de Janeiro, and it has been unofficially celebrated every year since then. In 2008, the United Nations by resolution designed June 8 as the official date.

The Middle School Portal 2: Math & Science Pathways (MSP2) project has developed resources that can support your teaching and learning about oceans. You can also search the MSP2 collection of resources for resources specifically developed for middle school science.

Ocean Systems Resource Guide
This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. This online resource guide focuses on earth/physical science including volcanic island formation and tsunamis; life science concepts including ocean ecosystems, food webs, and biodiversity; science in personal and social perspectives including pollution, endangered species and conservation; and related careers.

Earth’s Oceans Resource Guide
This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. This guide focuses on the oceans as a part of the Earth system: the link between oceans and climate; tsunamis; life science concepts such as ocean ecosystems, food webs, and biodiversity; real data – both sources of and projects that use real data; and related careers. There is also a section on the misconceptions commonly surrounding ocean concepts and finally the National Science Education Standards that these resource connect to. So even though you might not teach a unit called oceans, the oceans can be used as a context within an existing unit, such as ecosystems, energy transfer, systems thinking, or methods in science.

The Powerful Punch of a Hurricane
Centuries ago the Spanish named the storms that sunk their ships in the Caribbean Huracan, after the Mayan god of wind, storms, and fire. Whatever we call these tropical storms today – hurricanes, typhoons, or cyclones – we are amazed by their power to change or destroy habitats, damage property, and harm people.

We Are All Connected to the Oceans
This blog post describes a lesson that helps students to identify how humans impact the marine environment, make a personal connection with the oceans, and raise awareness of marine environmental issues. Using current marine articles and video clips, students will engage in their own environmental summit and write an action plan to raise awareness.

Coral Reefs Faced With Extinction
This post describes an article about the possible extinction of coral reefs and related National Science Education Standards.


We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 4/19/2012.

Investigating Cell Size

How big are cells? Ask most middle school students that question, and they’ll tell you that cells are very small – even microscopic! But what if you asked them to compare the size of cells in a whale and a shrew?

That’s the engaging scenario laid out in “Whale and Shrew,” a formative assessment probe from Uncovering Student Ideas in Science, Volume 2: 25 More Formative Assessment Probes (NSTA Press, 2007). The probe unearths a subtle, yet fundamental concept of cell theory – that there are natural constraints that necessarily limit cell size. How can you help your students reach this conclusion?

An inquiry-based activity provides an opportunity for students to answer the question, “How does the size of a cell affect its ability to exchange materials with its environment?” Or, more simply stated, “Why are cells small?”

These two activities could be used as is, or they could be adapted for a guided inquiry experience. Both involve analyzing how the surface area to volume ratio affects the rate of diffusion in cubes of various sizes. Each uses different materials and a slightly different procedure.

Cell Size and Division
Students test”cells” made of agar and phenolphtalein with sodium hydroxide. They observe the rate of diffusion (evident by color change) in 1x1x1, 2x2x2, and 3x3x3 cubes.

Experiment on Cell Surface Area and Volume
In this lesson, students test “cells” made of potatoes with Lugol’s solution. They observe the rate of diffusion (evidenced by color change) in cubes with a length of 0.5 cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm, and 3 cm. They also calculate the surface area, volume, and ratio of surface area to volume of all cubes.

How can you turn these activities into an inquiry-based lesson? We recommend starting with the probe to assess student thinking and spark interest. Next, you may ask students to generate a testable question based on the probe, or you may choose to provide the question for them. Students can then plan and conduct an investigation using the materials specified in either one of the lessons. Prompt students to generate claims and draw conclusions based on evidence from the investigation.

Teachers of younger students (grades 5 and 6) may wish to use the potatoes and Lugol’s solution, while an 8th grade teacher may have access to agar, phenolpthalein, and sodium hydroxide. Teachers may also modify this activity by removing the surface area and volume calcuations and instead relying on the qualitative observations made during the activity. Either way, students will gain new insight into why cells in any organism are small.

We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post updated 4/11/2012.