Looking for Life
A pair of objects, one living (such as an insect or plant) and one non-living (any inanimate object, preferably one not made from once-living material such as wood or leather)
An outdoor area to investigate, or images of a variety of living and nonliving things
Criteria for Life Log Charts – download PDF
3 small containers per group of 3 students (clear beakers or cups, or 3-oz. paper dixie cups)
Clean play sand, 150 ml per group of 3 students (50 ml for each of 3 containers)
Sugar, 15 ml per group of 3 students (5 ml will be added to each container)
Instant active dry yeast, 5 ml per group of 3 students (added to container B)
1 fizzing antacid tablet crushed to a fine powder per group of 3 students (added to container C)
Warm tap water (enough to cover each soil sample)
Cup for holding the warm tap water ( 1 per group of 3 students)
Paper towels in case of spills
- Prior to teaching the lesson, locate an outdoor area that contains a variety of living and nonliving things for students to investigate. If an outdoor area is not available, gather images of a variety of living and nonliving things.
- The day ahead of teaching the lesson, mix a batch of each soil sample (enough for the class) and store in airtight containers. Humidity will inactivate the yeast and cause the effervescent tablets to lose their fizz.
- Right before the lesson p our samples into jars for each group
- Be sure the water is not too hot. Yeast do well with warm tap water (about 50 C).
- Metabolic processes that show chemical exchanges, which may be detected in some sort of respiration, or exchange of gases or solid materials
- Some type of reproduction, replication or cell division
- Reaction to stimuli
- Ask students, “How do you know if something is alive?” and discuss the criteria students come up. Provide counterexamples as appropriate.
Example: Consider a bear and a chair— they both have legs, but one can move on its own and the other can’t; therefore, independent movement might be one characteristic that indicates life. Not every living organism needs legs or roots. But they do need a mode of locomotion or a way to get nutrients. Also, the bear breathes and the chair does not, another indication of life. Or consider a tree and a light pole. We know that a light pole cannot reproduce — it is made by humans — and we know that the tree makes seeds that may produce more trees. The tree also takes in nutrients and gives off gasses and grows. The light uses electricity and gives off light, but it is strictly an energy exchange and there is no growth or metabolic processes.
- Just before class, prepare jars of soil samples for student groups of three to four students.
- Place 50 ml of sand in each jar. (You will need 3 jars per team.)
- Add 5 ml of sugar to each jar. Label one jar in each set of 3 “A” and set aside.
- Add instant active dry yeast to the second jar in each set of 3 and label these jars “B.”
- Add a powdered fizzing antacid tablet to the remaining jars. Label these jars “C.”
- Give each group a set of three jars, a hand lens and Data Chart I.
- Besides Mars, where else might there be life in our solar system?
- Is it possible that there is life on a planet orbiting another star?
- How do scientists look for life when they can’t visit another world themselves?
Evidence of respiration, amino acids, etc.
- Learn about astrobiology, the search for life on other worlds
- “Exoplanets and the Search for Habitable Worlds” article and lesson
- Learn about exoplanets, planets outside our solar system
- Keep track of the current exoplanet discovery count
- Download the Exoplanet Travel Bureau posters
- Learn about exoplanet detection methods
- Ask an astrobiologist
- Life in the Extreme Activity Cards
- Astrobiology Science Learning Activities for Afterschool
- Types:CLASSROOM ACTIVITY
- Grade Levels:4 – 8
- Primary Topic:ASTROBIOLOGY
- Additional Topics:
- Time Required: 30 mins – 1 hr
- Next Generation Science Standards (Website)
Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction
Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms
Conduct an investigation to provide evidence that living things are made of cells; either one cell or many different numbers and types of cells
Construct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditionsUsing the fundamental criteria for life, students examine simulated extraterrestrial soil samples for signs of life. ]]>