Summary: It's a Small World After All! is actually two activities in one inquiry. In How Much Biodiversity Exists in a Pond Microcosm? students use microscopes to investigate the diversity of life that exists in pond water. In What Is the Effect of Rice on Microcosm Biodiversity? students conduct a controlled investigation to study the effect of a pollutant (rice) on a microcosm ecosystem. Note: The best time to start this inquiry is either September or May, when pond ecosystems are at their most active levels during the school year.

The easiest way to set up microcosms is in the context of a field trip where each team of students can fill its microcosm directly from a pond. However, since this may not be possible for all classrooms, the directions below explain how to set up microcosms at your school.
Note: When selecting a pond, keep in mind that small naturally occurring ponds tend to be richer in diversity than man-made ponds.

• Gather three five-gallon buckets with lids and a hand shovel.
• Visit a local pond the day before you plan to set up microcosms at school. Be sure to dress appropriately (e.g., shoes that can get wet, clothes that can get muddy).
• Fill a bucket 1/4-full with pond water and add enough algae for each microcosm. You may also want to add other pond plants (e.g., duckweed, pondweed) found on or near the surface.
• Fill another bucket completely with pond water. Avoid collecting larger consumers such as tadpoles as they will not survive in a microcosm.
• Fill the last bucket with a one-inch-thick layer of soil from the bottom of the pond.
• Secure lids tightly on all three buckets before transporting them in your car.

Ready...

• Gather two glass jars with lids per team. Note: One-quart mayonnaise jars or wide-mouth salsa jars work well.
• Choose a location for the buckets so that students can set up their microcosms in assembly line fashion.
• Place the soil bucket first, the water bucket second, and the producers bucket third.
• Choose a location to keep the microcosms where they can receive light, such as a window ledge. If there are no windows in your classroom, consider assigning students to take the microcosms outside each day or set up fluorescent lighting, such as a grow lab.

Get Set...

• Introduce the activity. "A microcosm is a mini world (micro=small, cosm=world). We will be studying microcosms over the next several days in order to learn more about pond biodiversity."
• Model how to set up a microcosm.

  • Add one or two spoonfuls of soil from the bottom of the pond.
  • Add enough water to fill the jar near the top.
  • Add enough plant life to cover the surface of the water.
  • Tighten the lid.
  • Return to your team area and observe the microcosms.
    Note: Expect microcosms to be cloudy for the first few hours before settling occurs.
    
• Group students into teams of four.

Go!!!

Ready...

• Copy a class set of the Thinksheet and Venn Diagram Data Sheet.
• Gather the following materials:

  • permanent markers (preferably one per team)
  • uncooked rice
    Note: Minute Rice will demonstrate an effect more quickly than long grain rice.

Get Set...

• Explain the purpose of today's lesson: To begin a controlled investigation to determine the effect of rice on the diversity of a microcosm.
• Introduce the term controlled investigation. Discuss the role of variables in a controlled investigation. (See Background Information.)
• Group students into their teams and have each team number from one to four in order to divide up the responsibilities listed below.

Go!!!

• Direct the #1 person to gather the microcosms.
• Direct the #2 person to label one jar C (for control) and the other jar T (for treatment).
• Distribute the Venn Diagram Data Sheet. Discuss how to use this sheet in order to compare and contrast differences in biodiversity. (See example.)
• Direct students to remove the microcosm lids and record initial observations (sight and smell) using the Data Sheet. Discuss findings as a class.
  Note: Often small consumers will be hidden in the plant layer. Carefully remove plants, then immediately return them to the microcosm in order to encourage consumers to move freely within the jar. Take care not to disturb the soil layer as it will cloud the microcosm.
• Distribute eight grains of rice to each team.
• Direct the #3 person to add the rice to the treatment jar.
• Distribute the Thinksheet and discuss. Complete the "Think It Through" and "Hypothesis" sections.
• Direct the #4 person to return the microcosms to their storage location.
• Direct students to wash hands with soap.

Ready...

• Copy a class set of the Venn Diagram Data Sheet.

Get Set...

• Explain the purpose of today's lesson: To observe changes that have occurred since rice was added to the treatment microcosm.
• Group students into their teams.

Go!!!

• Direct the #1 person to gather the microcosms.
• Distribute the Venn Diagram Data Sheet. Reinforce how to use this sheet in order to compare and contrast differences in biodiversity as rice (treatment) and time (both) begin to cause changes in the microcosms. (See example.)
• Direct the #2 person to remove the lid from the control jar.
• Direct the #3 person to remove the lid from the treatment jar.
• Direct students to record observations (sight and smell) using the Venn Diagram Data Sheet. Discuss findings as a class.
  Note: Expect the treatment jar to have a sewage smell.
• Direct the #4 person to return the microcosms to their storage location.
• Direct students to wash hands with soap.

Ready...

• Create an overhead transparency and/or class set of What Is the Effect of Rice Pollution on a Microcosm? Flow Chart.

Go!!!

• Read Horton Hears A Who! and discuss.
• Summarize the Main Points (See Background Information.)

  • Rice (a pollutant) reduces the diversity of life in a system.
  • The physical factor of limited space in the jar reduces the diversity of life in a system.
  • Why is the sewage smell in the treatment jar?
    • Bacteria grow and produce hydrogen sulfide (rotten egg smell) as one of their waste products.
• Discuss the Microcosm Pollution Flow Chart.
• Compliment students for appropriate behaviors during the lesson.
• Complete the "Make Some Sense Of It" section of the Thinksheet.
• Evaluation
• Formative: anecdotal notes of teams in progress, incidental questioning of students' rationale for what they are doing (during activity), observation of teamwork, status of the class (end of each unfinished activity day)
• Summative: Proficiency Assessment