How Many Bacteria Species Can Coexist on a Single Hand? (And do girls really have cooties?)

Sounds like a riddle, but it’s not trivial. We’ll get back to that in a minute. First consider the scenario: The class arrives from physical education. Today’s activity was mat ball, a variation of dodge ball involving lots of kids and lots of contact with balls and mats. They’re pumped, a little sweaty and out of breath, and one or two are a few seconds late—probably not because they were washing their hands! Would you have students wash their hands in this scenario? Not likely. It’s just not part of the lesson plan.

We accept a certain lack of sanitation mostly because it’s not feasible to allow 26-30 kids to wash their hands several times a day. We try to take solace in the hand sanitizers, though rumor has it there’s no substitute for warm water, soap and a minute of scrubbing.

Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shaped. Photo by Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU. Wikimedia Commons.

So what’s the big deal? Most bacteria on our skin are harmless or beneficial, right? How many could there be anyway? Well, CBCnews.ca recently published a story, Women lead men in bacteria types, hands down  that might surprise you. Researchers were surprised to find the incredible number of different bacteria species found among 51 college students’ hands and the very low number of species shared by all students. Further, there was a difference between left and right hands. And finally, there was a significant difference between men and women.

According to the news article,

They [researchers] identified 4,742 species of bacteria overall, only five of which were on every hand . . . The average hand harboured 150 species of bacteria. Not only did individuals have few types of bacteria in common, the left and right hands of the same individual shared only about 17 per cent of the same bacteria types . . .

Researchers suspect differences between left-and right-hand bacteria diversity have to do with each hand’s interactions with environment that can alter the hand’s conditions in terms of oil or salinity, for example. Differences between men and women might have to do with hormone production or slight variations in pH. Researchers commented that, for the subjects involved in this study, hand washing did not appear to remove the bacteria. It is important to note the study did not measure mass of bacteria present or population sizes for each species, only the diversity of species present.

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

The National Science Education Standards Content Standard F states:

As a result of activities in grades 5-8, all students should develop understanding of

  • Personal health
  • Populations, resources, and environments
  • Natural hazards
  • Risks and benefits
  • Science and technology in society

The ideas in this news article connect to the bullets above. The following discussion highlights the ideas in the list.

Ask students if they’ve ever had a bacterial infection. What caused it? What are bacteria? Many will state they are harmful, disease causing germs. How common do they believe bacteria are? Are they in contact with any right now? How do they protect themselves against bacterial disease? Lead students to understand that many kinds of bacteria are harmless and, in fact, beneficial. Our digestion is aided by bacteria, for example. Bacteria are used in the production of yogurt and cottage cheese, among other foods. You can show them photomicrographs indicating bacteria are distinct cells, but quite small. Bacteria impact our personal health in both positive and negative ways.

How are bacteria connected to populations, resources and environments? Remind students that a group of the same kind of bacteria living in the same area is a population. Can a human hand be an adequate environment with resources to support a bacteria population? How many kinds of bacteria do you think might be able to coexist on a single human hand? Entertain all students’ guesses. Share only the numbers from the story with them. How do their guesses compare with the numbers reported?

Try some true or false questions:

1. There is no difference in the kinds of bacteria found on the same person’s right and left hand.

2. Men and women have the same kinds of bacteria on their hands.

3. Among a group of people, there is a high number of different kinds of bacteria that all people share.

Share the rest of the findings reported in the article. Ask students to generate inferences to account for the variation reported. What questions can they generate related to the findings? What kind of tests do they think would be good to conduct next and why?

You can connect the idea of natural hazards to changes in bacteria populations if you care to. After a flood for example, the biggest threat is disease due to polluted water, from overflow of sewage mixing with drinking-water supplies. At times like these, the bacteria populations found on flood-ravaged persons’ hands can be expected to differ from those found under normal conditions.

What are the risks and benefits involved in controlling bacteria through various methods: sanitation, sterilization, irradiation, and antibiotics, for example? What are the risks and benefits of using helpful bacteria to control or minimize the occurrence of harmful bacteria in food?

What role does technology play in public health policies regarding available vaccinations, medicines, and public education campaigns? See the Centers for Disease Control webpage for additional ideas and information at http://www.cdc.gov/ncidod/guidelines/guidelines_topic_bacterial.htm

To find lessons and activities that would support this topic of study, please search the MSP2 Educational Digital Library – http://www.msteacher2.org/page/search-the-msp2-collection-of?q=bacteria&action=Search. Terms such as germs or bacteria will get you started.

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 November 10, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 2/29/12 by Jessica Fries-Gaither.

Antarctic Pale Ale: Another Use for Icebergs?

A brewery in Australia twice broke the Guinness record for the most expensive beer produced in modern times. The brewery’s secret: Nail Brewing used melted ice from an Antarctic iceberg. According to an article from oneindia News, brewer John Stallwood was looking for new ideas to bring attention to his small operation. His brother-in-law, who works on a ship that sails around Antarctica, took a helicopter crew to an iceberg, dug out some ice, and flew to Tasmania where the ice was melted. Stallwood sold the limited edition Antarctic Pale Ale at an auction to benefit the Sea Shepherd Conservation Society. The ale went for up to $1,850 per bottle. Some 30 bottles of the craft beer were produced.

The oneindia News article drew the attention of Laurel Bacque, who does communications and outreach for the IceCube neutrino observatory project at the South Pole. In her blog she describes the conservation society for her readers, saying its actions have been controversial. The society attempts to stop fishing ships that are hunting whales, sharks, and dolphins.

Icebergs were the theme of a recent issue of Beyond Penguins and Polars. Our columnists see them as a source of freshwater in the ocean, which can raise global sea levels, affect sea circulation patterns, and impact marine ecosystems. You’ll find many resources and amazing photographs for introducing K-5 students to icebergs in this issue – and lots for teachers of all grade levels.

Gulf of Mexico Oil Spill: A Middle School Perspective

Current events provide us with unique learning opportunities – ones that we need to take advantage of even if the consequences of that event are tragic. The Deepwater Horizon oil spill in the Gulf of Mexico is one such event. Not that it is the first oil spill that has had an impact on U.S. shores but it is by far the worst.

The last oil spill that most people can remember is the Exxon Valdez spill. It’s hard to believe that the Exxon Valdez oil spill happened in 1989 – 21 years ago. At the time, it seemed like we couldn’t ever have a worse spill. It was a watershed moment in U.S. environmental history and changed the way we consider and deal with oil and chemical spills in this country. On the 20th anniversary of the Exxon Valdez spill a movie, Hindsight and Foresight: 20 Years After the Exxon Valdez Spill, was released. The movie reviews the initial stages of the oil spill, shows how it changed U.S. laws and regulations, and identifies challenges for the future as it asks the questions: What does the twentieth anniversary of the spill mean, and what have we learned? Maybe not a lot, unfortunately.

The following resources provide amazing and tragic images of the spill, a chemistry perspective, a visual perspective (just how big is the spill compared to your town), and a podcast and lessons and resources collected by the Ohio Resource Center.

Gulf Oil Spill Could Eclipse Exxon Valdez Disaster
Slide show from NPR. An oil spill that threatened to eclipse even the Exxon Valdez disaster spread out of control and drifted inexorably toward the Gulf Coast as fishermen rushed to scoop up shrimp and crews spread floating barriers around marshes.

C&EN Special Issue: Disaster in the Gulf
Chemical & Engineering News, the magazine that goes to all members of the American Chemical Society, has devoted a special issue to the BP oil spill in the Gulf of Mexico. The articles are mostly available to anyone, but a few of them are only available to ACS members. They provide important scientific background for the oil spill, much of it useful for classroom discussions.

How Big Is the Deepwater Horizon Oil Spill?
See exactly where the oil spill is located in the Gulf of Mexico, and compare the size of the spill to the size of a city you are familiar with.

Oil Spills
The page has a number of visualizations and videos of the Deep Water Horizon incident as well as the Exxon Valdez along with general models of oil spills and software for modeling them. There are also teaching activities and materials for talking about these events in the classroom as well as a list of references that may be of use in the classroom. The content is targeted at undergraduate geoscience classrooms but if you are looking for a deeper understanding of what is happening this is a great place to go.

The Science of Oil Spills – Grades 6-8
The Ohio Resource Center has pulled together resources that support teaching and learning of multiple aspects of the Deepwater Horizon Gulf Coast oil spill. You’ll find a 10 minute podcast where Terry Shiverdecker and Jessica Fries-Gaither discuss how middle school teachers can use an Earth science systems approach to incorporate oil spill activities into their instruction as well as lessons, activities, and information that focus on everything from environmental aspects to the dispersants that are being used. Resources for K-2, 3-5, and 9-12 are also provided.

Connect with colleagues and talk about what you are doing in your middle school science classroom at the Middle School Portal 2: Math and Science Pathways (MSP2) social network – http://msteacher2.org.


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 12/09/2011.

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.

Lights Out March 27th for Earth Hour

At 8:30 p.m., local time, on March 27, hundreds of millions of people around the globe are expected to turn out their lights to observe Earth Hour. The event is a global initiative begun by the WWF (World Wildlife Fund) three years ago to recognize the need for action on climate change.

This year, 1,100 cities in 100 countries are participating. Lights will go off in some iconic landmarks in major cities. Tokyo Tower and the Brandenburg Gate in Berlin are among landmarks that will go dark for the first time this year, joining familiar U.S. sites, such as Mount Rushmore and the Golden Gate Bridge.

An online toolkit at the Earth Hour web site offers public service announcements, templates for local newsletters and other promotion helps, and classroom lesson plans.