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Creating an
Earth System I

Classroom activity:
Dogs and Turnips

Authors: Al Janulaw and Judy Scotchmoor


In this lesson students attempt to assemble a meaningful sentence by successively turning over cards with words on them. The point is made that we change our ideas of what a story may be as we gather more information. In addition, people who have similar information may not agree on its meaning. Science works this way.

Lesson Concepts:

Scientific ideas are developed through reasoning.
Theories are central to scientific thinking.
Science does not prove or conclude; science is always a work in progress.
Science corrects itself.

Standards Addressed:

Scientists develop explanations using observations (evidence) and what they already know about the world (scientific knowledge). Good explanations are based on evidence from investigations.

Grade Span: 6-8 or 9-12


  • One set of cut-apart sentence words for each group. If the sets are to be used again they should be laminated.
    - A printable HTML version of the words
    - A downloadable PDF version of the words

  • One D & T Worksheet for each group
    - A printable HTML version of the worksheet
    - A downloadable PDF version of the worksheet

Advance Preparation:

Laminate and cut apart the sentence words.

Time: 30 minutes
Grouping: threes or fours, then whole class

Teacher Background:

Scientists gather information and hypothesize about possible explanations of what they have found. Paleontologists collect specimens from a particular locality and work to assemble the story of what occurred in the past. As more information is gathered, hypotheses change. The literature is searched, collections are examined, information is shared with other scientists, and hypotheses are modified again and again. As scientists work toward a closer approximation of the truth, the premise is that reality exists In this activity, students gather information and work toward a closer approximation of the actual sentence. Note that there is a built-in ambiguity in the sentence and several reasonable "correct" answers are possible. Despite the artificiality of this activity, some aspects of the experience closely resemble real-life science.

Teaching Tips:

Encourage students to keep their "research" within their group until sharing time at the end. Let them know that you hope to have each group find out the "answer" on its own and the premature sharing would take away that opportunity for them.


  1. Pass our D & T Worksheets and word cards. Have each group spread out its word cards face down on the table.

  2. Tell the class that the words form one long sentence that also tells a story. The goal is to figure out the story from the words they turn over.

  3. Have each group turn over five cards at random and write what they think the story is on their worksheet (Hypothesis #1). After they have done this, ask them if it would help to have more information. They will, of course, answer yes.

  4. Have the groups turn over five more cards and record their new sentence on the worksheet (Hypothesis #2). After they have done this ask them if their idea of the sentence changed with more information. Discuss briefly, but do not have groups share their results, just yet.

  5. Have the groups turn over five more cards and record their revised sentence (Hypothesis #3).

  6. Allow groups to share with the class what they think the sentence says. Discuss the possible reasons why groups have different answers. Ask them how this might be similar to a paleontologist digging up ancient bones. (Scientists may not have all the information.) Ask why scientists might not agree on explanations of things. (Scientists may have different information or interpret things differently.)

  7. Allow all groups to turn over all the cards and to revise their hypotheses (Hypothesis #4). Have groups share out their "final" results. Chances are that the groups will still not have exactly the same sentences. Ask why they didn't. Ask why scientists may not have the same explanations for things even though they may have exactly the same information. (They may have come with different background information or interpret the same information differently.)

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