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.

Collecting and Analyzing Real Data

Data collection and analysis can be an avenue into meaningful mathematics, science, and problem-solving skills needed by students in the twenty-first century. And an answer to the student question, Why do we have to study math? can be found when teaching mathematics with a real-world statistics approach. Below are digital teaching resources that demonstrate how data and statistics are a vital part of learning mathematics in a meaningful context. The resource activities are often interdisciplinary, which makes them time-consuming to prepare, as additional expertise is often needed. But the payoffs can be huge: student engagement, in-depth learning, and a real-world context for learning mathematics.

One approach is to look at situations in your community or larger world issues and have the students frame questions to investigate. Students may develop a passion for scientific inquiry when a topic can be analyzed with numbers. Requiring quality work and including a component about sharing results with the community will add value to an interdisciplinary contextual learning experience. Teachers may want to enlist a community person to provide additional expertise. Whether thinking small activity or big project, be ready to be surprised at what the data analysis reveals!

Analyzing Numeric and Geometric Patterns of Paper Pool
Look out, pool sharks! Begin the study of data and statistics with this super student exploration where data are collected and analyzed while students apply mathematical topics studied in grades 6 and 7: factors, multiples, rectangles, and the meaning of being relatively prime. In the Paper Pool applet, a ball is hit from the lower left-hand corner of a grid-lined pool table at a 45-degree angle. Students modify the size of the rectangular pool table and observe how the ball always travels on diagonals of the grid squares. After gathering and organizing data, students look for patterns to predict the corner pocket into which a ball will fall and the number of side hits the ball makes as it moves on the table to a corner pocket. The goal is to determine how the number of hits, final pocket, and number of squares crossed depend upon the relative lengths of the sides of the pool table. Sounds like fun, doesn’t it?

Junk Mail (a mini project)
No one is immune from receiving junk mail, but just how much of it is really finding its way to your address? In this simple activity, data collection and analysis are a key part of a project to learn about the importance of recycling. For one week, students count and record the number of pieces of junk mail received in their homes. The display and organization of the data can be modified to address the data and statistics topics the class is working on.

WWW—Wonderful Web Weather
Just how on-target are those weather forecasters we watch and listen to? In this webquest, students work in groups to track online weather reports for several locations over the course of three days and determine the accuracy of forecasts. Students develop an understanding of how weather can be described by measurable quantities, such as temperature, wind, and precipitation as they find and compare weather data found on the Internet, chart and graph data, and present their conclusions about forecasting. This straight-forward activity is suitable for students who are just beginning their work with data and statistics.

The Global Sun Temperature Project
With this free online collaborative project, students measure the temperature and record the minutes of sunlight for one week. Data are collected on the web site, and average daily temperatures and amount of sunlight are compared. Students draw conclusions about how the distance from the equator influences temperature. If you like this collaborative project, be sure to check out Down the Drain: How Much Water Do You Use?, another collaborative data project from the Center for Innovation in Engineering and Science Education (CIESE).

The Gulf Stream Voyage
If ocean travel is your passion, this site offers a way to spend time at sea without ever leaving your classroom. Here is a science project that uses actual data to help students investigate the science and history of the Gulf Stream. Math students can greatly benefit from the opportunity to collect data and draw conclusions based on the data. In the lesson called Current Now, students use real-time data and satellite images to determine how the Gulf Stream moves in the course of a year. In another activity, students use data about water temperature obtained from ships and buoys to determine the course of the Gulf Stream.

Boil, Boil, Toil and Trouble: The International Boiling Point Project
Be part of an annual event: Enroll your class in this free Internet-based collaborative project. Students discover which factors–room temperature, elevation, volume of water, or heating device–have the greatest influence on boiling point. Students boil water, record their data, and send it via email to be included in the site’s database of results. Student activities focus on analyzing the compiled data to find answers to questions about how and why water boils.

Backyard Birding—Research Project
Birds are everywhere, and here are ideas for creating a data collection project. Work with a science teacher and, possibly, an industrial tech teacher to expand this multiweek activity into a cross-curricular project to help students see how data analysis can support an understanding of nature.

Population Growth
These nine online lesson/activities investigate population growth and its impacts. Students use archived census and demographic data from the U.S. Census Bureau to model population growth and examine how population change affects the environment. Teachers will want to carefully review this resource to choose the activities most appropriate for their students’ mathematics background. Linear, quadratic, and exponential functions are used in some lessons.
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 4/07/2012.

Amazing New Collection of Hands-on, Interactive Resources

The Lawrence Hall of Science at the University of California, Berkeley, has launched an online collection of hands-on, interactive resources to help informal educators in nonclassroom settings, such as museums and science centers, engage school-age children in science, mathematics, engineering, and technology learning. The web site is called howtosmile.org.

The web site provides both an enhanced faceted and a visual search capability; list-making features that provide a public or private online space to collect favorite activities and add teaching tips and ideas on how to use an activity; user-contributed videos, and other creative community functions that encourage users to rate and comment on activities. Some activities are available in Spanish. Special activity collections target those with limited mobility and individuals who are vision impaired. Built using open source tools, howtosmile.org also includes an open infrastructure to allow institutions to contribute links to useful activities and a free widget to embed howtosmile.org search results on any web page.

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 4/12/2012.

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.