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Origins: Back to the Beginning

Classroom Activities

Elemental Puzzler


To learn about the elements and their roles in the universe.

  • copy of the "Elemental Puzzler" student handout (PDF or HTML)

  1. All the elements known are formed in stars. This activity will help students explore some of the elements found in the Periodic Table of Elements and what role some of them play in the universe.

  2. Ask students how many elements they think exist in the Periodic Table (as of mid-2004,there were 115 elements; elements 116 and 118 were believed to have been found but scientists later retracted results).

    Review the table's basic organization (see Activity Answer for more information).

  3. You may want to note to students that the table is subject to change; new elements are added as they are discovered (only 94 of the elements exist naturally on Earth). Most of the heavier elements, which are created in particle accelerators or nuclear accelerators, exist for a fraction of a second before decaying.

  4. Have students do the puzzle. If they are having difficulty, point them to the following Web sites:

    WebElementsTM Periodic table

    Periodic Table of the Elements

    Elements in Fireworks
  5. When students have completed the puzzle, tell them that some of the elements listed in their puzzles have a special significance to the universe. Have students research answers to the questions on their handouts that are related to what role some of the elements play in the cosmos. Review student answers as a class, clarifying any misconceptions students may have.

  6. As an extension, have students research the astronomer's periodic table of elements that maps the abundance of the elements in the universe. Ask them to choose one of the elements on the table and create a poster about its role in the universe. Find one table at

Related Activities

Investigate what elements make up in the sun and learn about cosmic microwave background radiation in this American Museum of Natural History site that offers articles and student materials related to NOVA's "Back to the Beginning" program.

Activity Answer

Dmitri Ivanovitch Mendeleev published the first iteration of the Periodic Table of Elements in 1869. The modern table is divided into metal, nonmetal, and metalloid groups. Each group contains elements with similar physical properties. Metals make up 75 percent of the table.

In each horizontal row, the number of protons increases from left to right, starting with hydrogen, which has one proton. The number of protons in an element defines its atomic number. Elements along each row have the same number of principal electron shells (energy levels) while in an unexcited state, while elements found in vertical columns have similar outer electron configurations. Elements in the first two and last six columns have the same number of outer shell (valence) electrons (transition elements in the ten intervening columns follow a separate set of rules).

The five most abundant elements that make up atomic matter in the universe and the approximate percentages in which they occur (as a percentage of total number of atoms)are hydrogen (91.2%), helium (8.7%), oxygen (.078%), carbon (.043%), and nitrogen (.0088%). Approximate percentages by mass are (71.0%), helium (27.1%), oxygen (.97%), carbon (.40%), and nitrogen (.096%).

Some facts about hydrogen's role in the universe include that it is the most abundant element in the universe, it is the starting point for thermonuclear fusion, and it forms the molecular hydrogen clouds where stars are born.

Nitrogen and hydrogen combine to make ammonia. Iron is the final element created before a star undergoes a supernova explosion.

Solved puzzle
Links and Books

Web Sites

NOVA Web Site—Origins
In this companion Web site to the program, find out how life could have started and why water is needed for life; read about the latest discoveries in origins research; use raw data to assemble the famous Eagle Nebula image; insert your own values into the Drake Equation; decode cosmic spectra; and more.

The Electromagnetic Spectrum
Provides an activity that allows students to identify substances based on the visible spectra they emit.

Timeline of the Universe
Offers a tutorial that traces the 15-billion year history of the universe, including the big bang, element formation, planetary system formation, the creation of Earth-like planets, and the chemistry of life.

Universe Forum: Learning Resources
Includes FAQs about the cosmos, information about the Center for Astrophysics' online telescope network, and links to additional lesson plans and activities.

WMAP Related Educational Resources
Provides an overview of the project, classroom exercises, commonly asked questions about the universe, a glossary, and more.


Couper, Heather and Nigel Henbest. Big Bang: The Story of the Universe. New York: DK Publishing, Inc., 1997.
Follows the story of the universe from its birth to the present and beyond.

Skurzynski, Gloria. Waves: The Electromagnetic Universe. Washington, D.C.: National Geographic Society,1996.
Simplifies and clarifies the electromagnetic spectrum with colorful images and everyday applications.

Stwertka, Albert. A Guide to the Elements. New York: Oxford University Press,1996.
Serves as an introductory resource, beginning with the basic concepts of chemistry and tracing the history and development of the periodic table of the elements. Each element is presented individually and accompanied by a photograph and practical application.


The "Mission: The Search for Life" activity aligns with the following National Science Education Standards:

Grades 5-8

Physical Science

Science Standard B:
Physical Science

Properties and changes of properties in matter:

  • There are more than 100 known elements that combine in a multitude of ways to produce compounds, which account for the living and nonliving substances that we encounter.

Grades 9-12

Physical Science

Science Standard B:
Physical Science

Structure and properties of matter:

  • An element is composed of a single type of atom. When elements are listed in according to the number of protons (called the atomic number), repeating patterns of physical and chemical properties identify families of elements with similar properties.

Classroom Activity Author

Developed by WGBH Educational Outreach staff.

Teacher's Guide
Origins: Back to the Beginning

Video is not required for this activity

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