Rock Flip

Objective

In this activity, students will flip over a board or rock in their field site and count the critters they find beneath it. Sampling is a common technique used by scientists to get an accurate population sample for small critters. By collecting this data over a period of time, students can establish a baseline population for their field site and note how the population changes over time.

Making the connection:

Activity

Hypothesize

What types and numbers of soil critters can you find under a rock or board at your field site?

Plan it!

  • If you haven't already done so, choose a field site and map it in your field journal.
  • At least a week before you do this activity for the first time, place your board out on a grassy area so that it lays flat on the ground. If possible, the board should be hidden under leaf litter, grass clippings, etc. If you plan to collect this data over a period of time, be sure to place your board where it will not be disturbed or disturb others. If this is not possible, look for large rocks already in your field site that you can turn over instead.
    Sampling from different locations at the field site and collecting the data on multiple occasions will allow opportunities for students to analyze comparative data over time.
  • Decide how often to check your board or rock. 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 this data daily?
    • How might your results be affected if you collect this data monthly?
    • How might your results be affected if you collect this data annually?
  • 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.

Do it!

  1. Flip over the board or rock.
  2. Count the number of each different type of critter you find under the board or rock. You should work quickly to count the critters before they run away.
    If you have anticipated the types of critters you may find, each student in the group can be responsible for counting one type of critter, with one student responsible for any critters not assigned to others. Alternatively, each student can count all of the organisms. The results can be averaged, with the high and low counts dropped. After counting, students can then take more time to observe the organisms and to look up any unknown organisms in the field guide.

Record it!

  • Record the types and number of critters you find on the Rock Flip worksheet . If you are working with a group, have one person record the data while others count. If you are not sure what a critter is, draw it or record a description of the critter.
  • After you have counted and recorded the organisms you found, look up any unidentified organisms in the Underground Adventure Field Guide . Record this identification on the worksheet.
  • Add the worksheet to your field journal.

Remember, be sci-wise!

  • If you are able to collect data from beneath your rock or board over a period of time, remember to collect the data at the same time of day each time and to collect it on a regular basis.
  • Treat the critters you find with respect. Do not handle them unnecessarily.
  • You will 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 under the rock or board? Were there more critters than you expected to find? Fewer?
    The types of critters students find will vary. Most students will probably expect to find worms, ants, and spiders, and may be surprised to find some creatures they've never seen up close before.
  • Based on the data you collected, do you think your hypothesis was correct or incorrect? Why?
    Answers will vary.
  • How did the types and numbers of creatures you found here differ from the creatures you found in the soil sample in Looking for Life? What might cause those differences?
    Students will likely see greater numbers of critters under they rock or board than they saw in the soil sample. The rock or board provides a good micro-habitat for some soil critters, so you can expect a greater concentration of critters on the surface there than in other places in your field site.
  • How did the critters react when you moved the board or rock? Did they move quickly or slowly? Why might they have reacted like this?
    Some critters will likely move quickly when the board or rock is moved, although others will not. One reason these critters may move quickly is that some of them prefer dark places and so will move quickly to get back out of the light.
  • What effect does moisture have on the types and numbers of creatures in the soil?
    Some soil creatures are more likely to be found near the surface when the soil is moist.
  • What patterns or links did you notice between the creatures found in the soil and the air temperature? Did the air temperature have more or less of an effect on the critters you saw in this study than they had on the critters you saw in Looking for Life?
    Some creatures may avoid the surface of the ground under certain weather conditions and temperatures. The effect is likely to be less in this study than in Looking for Life.
  • If you were to continue collecting this data for a whole year, what differences would you expect to find? What differences would you expect to find if you collected this data over 10 years?
    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. This type of monitoring is effective over a long period of time, such as 10 or more years. This makes it possible to establish a "baseline of health" or a population size for that specific area. If you were to see major declines or increases in population size over a short amount of time, this may be due to human impact.
  • Fill in this section of 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 make connections between the data they collected here and the data they collected in other activities to help answer the research question.

Extensions

  • Bug Moves
    Students probably observed the soil critters moving quickly when they flipped the board or rock. Ask students to draw a bug and animate its movements based on what they observed. Students can do this by creating a flip book or using a computer animation program.
  • Bug Art
    Ask students to create a piece of music, a dance, or a piece of art inspired by the activity they found when they flipped the board or rock. The art doesn't need to depict the critters they found, but should give the same sense of movement.

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