When Did the Grand Canyon Begin to Form?

South Rim, Grand Canyon. Image courtesy of Kimberly Lightle.

This blog post draws from several news sources — washingtonpost.com, The New York Times, 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 (free registration is required to view this article). 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 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 counter-argues 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 three 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?


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 14, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 11/16/2011 by Kimberly Lightle.

Newest Issue of Beyond Weather and the Water Cycle Highlights the Science of Climate Study

Scientists recording data on Sperry Glacier. Photo courtesy of glaciernps, Flickr.

The just-published issue of the free, online magazine Beyond Weather and the Water Cycle gives K-5 school teachers a unique opportunity to introduce the science behind weather and climate change to young students with engaging lessons and proven reading strategies.

Each issue of the magazine takes its theme from one of the widely accepted principles of the climate sciences. The theme of the September 2011 issue is “We Study Earth’s Climate.”

Designed to integrate science and literacy instruction for educators in K- grade 5 classrooms, this and earlier issues provide background articles on the related science and literacy topics and their connections to the elementary curriculum. Science and literacy lessons to use in the classroom become a part of unit plans for grades K-2 and 3-5 and are aligned with the national standards for science education and English language arts.

An original story, titled  How Do We Study Climate?, gives young listeners and readers chances to use their comprehension skills on informational text. The story is available at two reading levels and in three different formats.  Selected children’s books on climate and weather are highlighted in a bookshelf feature.

Two articles are devoted to teaching young people to evaluate information from web sites and to use video clips from agencies that work with weather satellites, balloons, and buoys to learn about data collection.

Readers are welcome to add their ideas and suggestions on articles by leaving comments. They can also easily share and bookmark content by using the embedded AddThis buttons.

Beyond Weather and the Water Cycle is funded by a grant from the National Science Foundation (NSF) and produced on the campus of The Ohio State University (OSU) in Columbus, Ohio.  All past issues of the magazine are available from the homepage of the magazine.

Kimberly Lightle, director of digital libraries in OSU’s College of Education and Human Ecology, School of Teaching and Learning is the principal investigator of the project as well as a contributing writer. Jessica Fries-Gaither is the project director of Beyond Weather and the Water Cycle as well as the award-winning sister publication, Beyond Penguins and Polar Bears.


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updated 12/07/2011.

Celebrations of First South Pole Expeditions

This winter will mark 100 years since explorers first reached the South Pole within weeks of each other — Roald Amundsen on December 14, 1911, and Robert Falcon Scott on January 17, 1912. Commemorations, exhibits, and books are expected; some events have already begun and at least one book published.

Norway will celebrate two anniversaries in 2011, Amundsen’s successful expedition to the South Pole and the birth of Arctic explorer Fridtjof Nansen 150 years ago. Some 130 events are planned in Norway and abroad.

British explorers Robert Falcon Scott and Ernest Shackleton and their sponsors were motivated more by scientific interest than the glory of reaching the South Pole first, according to Edward Larson, author of a new book on the expeditions, An Empire of Ice (Yale University Press, 326 pages, $28). With the deaths of Scott and his four-man team on their return from the South Pole, public attention turned more to the courage they showed as they died one by one than to the new knowledge gathered by them and other members of the expedition. Politicians used the deaths as examples of serving one’s country and to rally support for their causes.

A professor of history and law at Pepperdine University and a Pulitzer Prize-winning historian, Larson calls his book “neither a paean to Shackleton’s leadership nor a critique of Scott’s choices.” The publisher says the book “offers a new perspective on the Antarctic expeditions of the early twentieth century by looking at the British efforts for what they actually were: massive scientific enterprises in which reaching the South Pole was but a spectacular sideshow.” Scott, the publisher points out, has been portrayed as a “a dashing incompetent who stands for little more than relentless perseverance in the face of inevitable defeat.”

Most of the 32 explorers Scott took with him were British scientists. They found that Antarctica was a continent not an archipelago, learned that emperor penguins lived on sea ice, and retrieved fossils that would show a warmer climate in the past.

One of Scott’s explorers, Apsley Cherry-Garrard, wrote his own account of the purpose of the expedition, the accomplishments, and the discovery of Scott’s frozen body — The Worst Journey in the World, available online in Project Gutenberg. His worst journey could have been the one he made with the expedition’s biologist, Edward Wilson, to find embryos of emperor penguins. Scientists back in Britain thought the embryos would provide the link between dinosaurs and birds. Cherry-Garrard, Wilson, and Birdie Bowers had to find the penguins in the Antarctic winter (June to August) when the birds incubate their eggs. They had to travel 130 miles to find the penguin colony on sea ice in minus 60 degrees Fahrenheit and build an observation post in a blizzard. Their teeth cracked from chattering in the cold, but they pickled embryos in alcohol and took them back to London.

The three men were the first to witness the emperor penguin’s huddles, its behavior during hatching, and the care the bird gives to the chicks. Cherry-Garrard’s book describes life and work at the base camp in preparation for the South Pole expedition and the long wait for Scott’s return. While some believe Scott’s choices in sledge hauling, clothing, and rock gathering were causes of his return party’s demise, others note that unexpected cold weather (10 degrees Celsius below normal for three weeks) and a blizzard accounted for the team’s inability to reach the nearby store of supplies on the return trip. Otherwise, they would have probably reached the base camp.


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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? 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.

Celebrate Women’s History Month with STEM Stories

The STEM Stories website features a growing collection of digital resources that highlight the lives and work of individuals involved in STEM fields (mainly women). It combines compelling personal stories and multimedia to interest intermediate and middle school students in STEM subjects and careers.

From the In the Spotlight menu, you’ll meet 10 present-day women who are featured in depth, with interviews, photo albums and more.  They include dolphin communication researcher Diana Reiss, atmospheric chemist Susan Solomon, biologist and astronaut Millie Hughes-Fulford, and robotics engineer Heather Knight. (Heather helped work on the Rube Goldberg machine sequence for the OK-Go music video This Too Shall Pass).  On the Clips tab, the database includes short videos that introduce individuals working in varied STEM careers.  The Profiles tab lets you search biographies about women working in STEM fields throughout history.  Some include photo albums, such as Mary Pennington, Rachel Carson, and Virginia Apgar. (Tip:  double-click on images to see a larger view).

The project team, headed by Lois McLean and Rick Tessman (McLean Media) created STEM Stories with girls in mind, drawing on design ideas from an after-school club for at-risk middle and high school girls. In a 2010 pilot, more than 200 students (Grades 4–7) in Nevada County, California, used the site in classroom activities. In one school, fourth- and seventh-grade students worked in pairs to create pop-up books based on featured individuals. Survey results found no major differences between the responses of boys and girls. In fact, teachers reported that students did not even comment on or question the site’s emphasis on women. And, although the website focuses on personal stories, most students also reported learning something new about science and engineering.

STEM Stories was funded through a grant from the NSF’s Research on Gender in Science in Engineering Program (#HRD-0734004). New content is being added every month, including more current and historical photos, profiles, videos, and interactives.

To introduce your students to the STEM Stories site, try these activities:

STEM Stories Treasure Hunt

STEM Stories Crossword Puzzle

STEM Stories Lesson Ideas


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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? 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.

History and Nature of Genetics and Heredity

While Gregor Mendel’s contributions are certainly important for both their methodology and findings, they are not the only historically significant aspect of genetics and heredity. What were the cultural norms and views in times past? How did those views impact the advancement of science?

History of Genetics Timeline
This well-organized table starts with Charles Darwin and Alfred Wallace in 1858, giving teachers a good foundation or review of how knowledge of genetics and heredity developed. However, it is interesting to ponder how people thought about reproduction and heredity prior to Darwin, since those concepts influenced the questions, if any, that were posed.

And Still We Evolve: Section Five: Heredity and Modern Genetics
This self-published handbook addresses ancient views (we cannot call them theories since they lacked supportive empirical evidence resulting from rigorous experimentation) of preformation, incapsulation, and epigenesis. Though your students may not admit it, they could have held, or may still hold similar views themselves.

A Mendel Seminar
A lesson for high school students in advanced biology revolves around Mendel’s original paper, Experiments in Hybridization (1865). The structure and support provided in annotations enable the learner to make sense of, and gain insight into, Mendel’s reasoning, methods and conclusions.

Thomas Hunt Morgan and Sex Linkage
This article summarizes Morgan’s work and includes tables and graphics for a clear presentation. It includes a section titled The Context of Morgan’s Discovery, from which the following quote is extracted, giving insight into his views:

Morgan, however, had long resisted the idea that genes resided on chromosomes, because he did not approve of scientific data acquired by passive observation. Furthermore, Morgan was not convinced that traits couldn’t morph into new forms in an organism based on the blending of parental contributions, an idea leftover from pre-Mendelian scientists. Morgan was sure that . . . researchers who promoted the chromosome theory of inheritance were looking for an easy answer as to how independent assortment occurred in gamete formation, because he believed they ignored counterevidence in the face of excited conviction. In fact, he thought that the concept of genes was at best an invention intended to link the mysterious paths of chromosomes :and discontinuous inheritance patterns.

This post excerpted from Middle School Guide to Reproduction and Heredity


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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? 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 11/18/2011.