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  • Tips & Modifications

    Tip Teacher Tip

    To save your students' data for grading online, register your class for free at the High-Adventure Science portal page.


    The activity is part of a sequence of activities in the Is There Life In Space? lesson. The activities work best if used in sequence.


    This activity may be used individually or in groups of two or three students. It may also be modified for a whole-class format. If using as a whole-class activity, use an LCD projector or interactive whiteboard to project the activity. Turn embedded questions into class discussions. Uncertainty items allow for classroom debates over the evidence.

    1. Activate students' prior knowledge about atmospheres.

    Tell students that Earth's atmosphere is a mixture of gases, 78% nitrogen, 21% oxygen, and 1% all other gases, including carbon dioxide, water vapor, argon, etc. Ask: 

    • What gases do you think are necessary for life? (Students may state that oxygen is necessary for life, but there are many forms of life on Earth that do not need oxygen.)
    • How do you think scientists determine if a planet has an atmosphere and what gases are in its atmosphere? (Students may state that scientists have to send probes to the planets to sample their atmospheres. Tell students that most planets are too far away to send probes to get information directly.)

    Let students know that scientists use light from planets' stars to analyze the atmospheres of the planets.


    2. Discuss the role of uncertainty in the scientific process.

    Introduce students to the concept of uncertainty in the scientific process. Explain that science is a process of learning how the world works and that scientists do not know the “right” answers when they start to investigate a question. Tell students that they can see examples of scientists' uncertainty in determining whether or not the data collected from telescopes show the presence of planets.


    Show the Kepler Planet Candidates graph from the NASA Exoplanet Archive. Tell students that the red dots indicate potential planets the Kepler telescope has detected and the blue dots indicate the planets the Kepler telescope detected and have been confirmed by other means. Ask:

    • Why do you think there are more red dots than blue dots (more potential planets than confirmed planets)? (The telescope may detect planets that are not there. The technology may not be good enough to tell the difference between a planet and some other phenomenon.)
    • Why do scientists need to independently confirm the presence of planets? (Scientists need to check the accuracy of the telescope's predictions of a planet. If the telescope shows a planet and the scientists confirm that it is a planet, then the scientists can spend more time trying to learn about the planet.)

    Let students know that they will be asked questions about the certainty of their predictions and that they should think about what scientific and model-based data are available as they assess their certainty with their answers. Encourage students to discuss the scientific evidence with each other to better assess their level of certainty with their predictions.


    3. Introduce and discuss the use of computational models. 

    Explain the concept of computational models, and give students an example of a computational model that they may have seen, such as forecasting the weather. Project the NOAA Weather Forecast Model, which provides a good example of a computational model. Tell students that scientists use planetary models to predict the motion and apparent brightness of stars if planets are present and to predict the habitability of planets. Explain that there are many different types of models and that they will be using simple models of planetary motion in this activity.


    4. Have students launch the Looking for Signs of Life interactive.

    Provide students with the link to the Looking for Signs of Life interactive. Divide students into groups of two or three, with two being the ideal grouping to allow students to share computer workstations. Tell students they will be working through a series of pages of data with questions related to the data. Ask students to work through the activity in their groups, discussing and responding to questions as they go.


    NOTE: You can access the Answer Key for students' questions—and save students' data for online grading—through a free registration on the High-Adventure Science portal page.


    Tell students this is Activity 5 in the Is There Life in Space? lesson.


    5. Discuss the issues.

    After students have completed the activity, bring the groups back together and lead a discussion focusing on the following questions:

    • How can scientists tell what elements are in a mixture of gases? (Scientists use spectroscopy to detect which elements are in a mixture of gases. Each element absorbs light in a unique pattern. By analyzing the light going into the atmosphere and the light coming out of the atmosphere, scientists can determine what elements are in the atmosphere.
    • How can scientists use planetary spectra to search for life on other planets? (Scientists can analyze the composition of the planet's atmosphere. If the planet has gases that are conducive to life or indicate that life may be present, they can then investigate further for life.)

    Informal Assessment

    1. Check students' comprehension by asking students the following questions:

    • How can you use light to determine which elements are in a mixture?
    • Would the spectrograph of a planet's atmosphere have more, fewer, or the same number of lines as the spectrograph of the planet's star? Why?

    2. Use the answer key to check students' answers on embedded assessments.

  • Subjects & Disciplines

    • Space sciences
  • Science
    • Earth science