The Grand Time Game

The Grand Time Game is a collection of middle school activities to teach about geologic time. It was developed by Dr. Bill Witherspoon, geologist at Fernbank Science Center, a unit of the DeKalb County, Georgia Public Schools. The Grand Time Game has been used in a wide range of classrooms. It consists of the following elements:

  • A dynamic tabletop model that demonstrates the geologic history of the Grand Canyon.
  • A script in which students "report" selected events along the geologic time scale as the instructor operates the model. (pdf file: 97K)
  • Overhead transparencies of sites in the Grand Canyon area and Georgia that the instructor shows to illustrate the story. (pdf file: 394 K)
  • An activity sheet on which students tag events to the geologic time scale as the story progresses. (pdf file: 46 K). It shows two time columns – one with the absolute years, the other with the time scaled to one minute representing one thousand years. In the scaled down version, the earth is about eight years old and the Cambrian Period begins on January 1 of the final year.
  • A card game about fossils and geologic time, played in groups of three or four students after the script reading.
  • An activity which allows further study of the assemblage of four fossils the student selected in a round of the card game.
  • The potential to use cards after the game to paste into a calendar or display along a time line that represents the span of geologic time.


Tabletop Model

The model allows the instructor to show the sequential deposition of major sedimentary layers (rock units) in the eastern Grand Canyon area from about 550 to 150 million years ago. The floor is lowered to demonstrate the subsidence of the old land surface below sea level, which permitted the adding of new layers. A 170-million year halt to the subsidence and deposition beginning in the Late Cambrian Period demonstrates the concept of an unconformity.

After all the layers have been added, while students have their attention on written materials, the stack of layers is quietly switched for a duplicate stack constructed with removable cutaway pieces. Then as the instructor lifts the floor of the model to demonstrate uplift, the cutaways are removed, taking three stages to demonstrate the progressive carving of the canyon by the Colorado River.

Click here for instructions on building the model. The materials are relatively inexpensive, but there are many hours of labor, especially in cutting and painting foam layers. We are evaluating the possibility of manufacturing the Grand Time Game, including the model if there is sufficient demand. If you are interested in being on a waiting list to purchase a "Grand Time Game" including the tabletop model, please e-mail

  Card Game

Students enjoy playing several rounds of a card game that demonstrates important concepts about fossils and the geologic time scale. Their scoring sheet (pdf file: 50K) is copied to the back side of the matching activity.

The overall goal of the game is to “collect” an assemblage of four fossils that will tell a realistic, specific story about the geologic past.  The organisms must have overlapped in geologic time in order for a player to earn a non-zero score.  After that, points are awarded for organisms that share a common habitat, form a complete food chain, and point to as short as possible an interval of geologic time.  

Before students can play the game, they must learn the ways in which they can make points. They learn by scoring the results of three fictitious rounds as shown on overhead transparencies (pdf file: 407 K) in their "Round 1" through "Round 3" columns. (For the solutions to the sample round scoring, see pdf file: 45K.)

Students are arranged in groups of (preferably) four or three. Each group receives a deck of thirty-two cards. The dealer can be chosen as the person closest to the classroom door. Four cards are dealt to each player, then the remainder of the deck is placed faced down and one card is turned over to begin the discard pile. The player to the dealer’s left begins. In a player’s turn, he or she may draw either (and only) from the top of the deck or the top of the discard pile. He or she decides whether the drawn card would improve his or her score, and discards the same card or another face up on the discard pile.

The round continues until the instructor calls time (about five minutes). Each player then scores his or her four cards using the scoring sheet. If students exhaust the cards in the deck during a round, they can shuffle the discard pile and begin as before.

To make a card set, print the color backs onto cardstock first (pdf: 31K), then use a copier to put the card fronts (pdf: 187 K) on.

After each played round, there is further opportunity for students to investigate their four-card fossil assemblage.  Using an “Assemblage Activity” form (pdf: 44 K), students record all the information about each fossil.  They have an opportunity to earn bonus points based on the shortness of their assemblage’s time range.  To complete the activity, students write a paragraph about the assemblage, describing the relationship of the four fossil organisms. 

Using cards in a calendar time line

As a follow-up activity, students can paste card images into a calendar brought from home. On each card, the organism’s span in geologic time is shown in three ways. The "era" symbols pC, Pz, Mz, and Cz are centered at the bottom of the card. The times of origin and extinction (if any) are shown in millions of years on either side of the era symbols. Lastly, unless the organism began in the Precambrian, the time of origin is shown as a calendar date based on the one minute to one thousand years scale.

By using this last date as a guide, students can paste cards into a calendar and discover how crowded the latter part of the year will be!