Looking for Life

Objective

In this activity, students will look for, identify, and count the organisms found in soil samples from their field site.

Making the connection:

  • By collecting and observing soil samples over a period of time, students can learn about the types and numbers of organisms living there.
  • By doing this activity along with the Soil Temperature Test, Compaction Test, Percolation Test, Texture Test, and Mud Shake, students can learn how the physical properties of soil affect the critters that live there.
  • By doing this activity along with Air Temperature and Cloud Cover, they can learn about how these environmental factors affect the creatures living underground.

Activity

Hypothesize

What types of creatures live in the soil at your field site and how many of them are there?

Plan it!

  • If you haven't already done so, choose a field site and map it in your field journal.
  • Decide how often to collect soil samples. If you are working with a group or as a class, you should decide together. As you decide, think about these questions:
    • How might your results be affected if you collect daily samples?
    • How might your results be affected if you collect monthly samples?
    • How might your results be affected if you collect annual samples?
  • Before you get started, review the Underground Adventure Field Guide to become familiar with the organisms listed there. Print out a copy of the Underground Adventure Field Guide to take with you into the field. You can also prepare by doing the Critter Quiz online activity. Note: Field guide pages can be laminated to protect them from dirt and moisture.
  • Once you are at the field site, each student or group of students should set up a quadrant in which to work.
    Spreading out over the field site and taking multiple measurements will ensure that a representative sample is recorded and will allow opportunities for students to compare their data with data taken at other areas of the site. If the ground is frozen at your selected field site, you should select another day for this test.

Do it!

  1. Within your quadrant, dig a small hole with a trowel or spoon to a depth of about 2 inches. If you have difficulty estimating the depth, you can use a plastic ruler to check your estimate.
  2. Place the soil from the hole onto a white paper plate to get a better look.
    Students can also use a piece of white paper if a paper plate is not available.
  3. Search through the soil for organisms. Use a magnifying glass to get a closer look at the organisms in your soil sample.
    Students should work fairly quickly to find the different types of creatures and to count them. They can then take more time to observe and draw the organisms. They may need to gently herd escaping critters back onto the plate as they work.

Record it!

Remember, be sci-wise!

  • If the ground is too hard to dig in, try moving to a nearby spot.
    If the ground is frozen throughout your field site, you should schedule this activity for another day.
  • Be careful while digging with a trowel. The edges are sharp.
  • Handle the magnifying glass carefully to prevent it from breaking.
  • Even if you think you know what an organism is, it is a good idea to double check with the Underground Adventure Field Guide .
  • Handle all insects gently and respectfully. Return the organisms and soil to the ground when you have finished.
  • Be sure to clean and properly store all equipment.
    You'll need to prepare for the dirt and mud that will be brought back on students' shoes. Consider having students bring in an old pair of sneakers or boots to use for your field activities. Students can leave their dirty shoes "at the door" and then shake or brush them off when the mud has dried.

Assessment and Reflection

  • Did you find the creatures you expected to find in the soil sample?
    The types of critters students find will depend on many factors. Most students will probably expect to find worms, ants, and spiders, but may be surprised to find some creatures they've never seen up close before. If students do not find many critters in their sample, that can be informative as well.
  • Based on the data you collected, do you think your hypothesis was correct or incorrect? Why?
    Answers will vary.
  • How did the creatures compare to their descriptions in the Underground Adventure Field Guide ? Did they look the way you expected them to?
    By comparing their own observations with field guide descriptions, students begin to develop an understanding of group characteristics and individual variations.
  • How might the depth of the soil sample affect the types of creatures found there? What data could you collect to test this?
    Different soil creatures can be found at different depths. To learn more, students could revise the experiment to dig deeper as they collect their soil sample.
  • What effect might moisture have on the types and numbers of creatures in the soil? What data could you collect to test this?
    Some soil creatures are more likely to be found near the surface when the soil is moist.
  • What relationship did you notice between the creatures found in the soil and the air and soil temperature?
    Some creatures may avoid the surface of the ground under certain weather conditions and temperatures.
  • What would you expect to observe in your soil sample if you used a microscope?
    Students should realize that there are many more creatures in the soil than can be seen with the eye or a magnifying glass. Some are so small they can only be seen with a microscope.
  • If you were to continue collecting soil samples for a whole year, what differences would you expect to find?
    In some climates, you can expect to find different organisms in the soil at different times of year. In addition, some creatures may be in different life stages, and look quite different, at different times of year.
  • How do the types of creatures found in the soil affect the soil? How do they affect the plants? Animals? People?
    Some possible answers include the negative effects on agriculture and gardening from creatures considered "pests." On the other hand, some organisms are vital to the health of soil. Soil organisms are part of the food chain and have a direct or indirect relationship with other organisms in the ecosystem.
  • How does the data you collected here differ from the data you collected in Rock Flip? Why might this data be different? What data could you collect to try to prove your hypothesis?
    Answers will vary.
  • Complete this section in the Soil Biodiversity Overview worksheet .
  • Looking at the bigger picture, how might the data you collected here help you to answer your research question?
    Answers will vary, but students should be able to connect the data they collected in this activity with the data they collected in other activities to answer their research question.

Extensions

  • Adaptation: A Day In the Life
    Have students pick a favorite soil organism and write a story about it. Ask them to imagine that they are that soil organism, and write about a "day in the life" of this creature. What did they do, and whom did they meet? Have students do some research on their creature by using the Underground Adventure Field Guide and other resources. Be sure to have them include information about the organism's prey and predators.
  • Sampling
    You can't count all the critters at your field site. Instead your students, like all scientists, counted only a sample. Through this sub-sampling technique, students can use math to estimate the total number of each type of organism can be found at their field site:
    1. Find the area of a quadrant (the length multiplied by the width).
    2. Figure out how many quadrants there are in the field site (the total area of the field site divided by the area of a quadrant).
    3. Multiply the number of each creature found in one quadrant by the number of quadrants in the site to estimate the number that would be present in the entire field site. (For example, 5 ants multiplied by 400 quadrants equals 2,000 ants.)

↑ Return to top ↑