• During the lesson, confer with students to determine if they understand ecological balance. This can be done by asking questions of the entire class or asking students individually.
• Place students in small groups. Put the following question on the board: How do organisms in your body and your environment help to provide an ecological balance? Students should discuss the questions within their groups. After giving students about five minutes, meet with each group. Listen to their responses and make corrections to their understanding.
• Collect science journals for individual assessment.
• Collect and check the Dirty Observations Lab worksheet, the Competition—Guided Reading Questions, and the Examples of Symbiosis worksheets.

In preparation for the lesson, read through the Dirty Observations Lab (S-7-7-2_Dirty Observations Lab.doc) and select an area on the school ground where it is permissible for students to remove small soil samples.

Day 1

Begin the lesson by writing the word ecology on the board. Say to students, “Today we will continue studying ecology. Give me some examples of what you believe an ecologist studies.” Record student responses as they give them.

Explain to students that ecology is a branch of biology. Ecologists are scientists who study ecology. The term ecology comes from Greek words that mean “study of the household.” Ask students to infer how ecology is like a study of a household.

Hand out a copy of the Ecology Vocabulary Worksheet (S-7-7-2_Ecology Vocabulary Worksheet and KEY.doc) to each student. Have students work in cooperative learning groups to complete the “What We THINK This Term Means” column on the worksheet.

After groups have completed the Ecology Vocabulary Worksheet, check their responses as a class, correcting student understanding where necessary. Define each term on the board and have them fill in the “This IS What This Term Means” column on the worksheet.

Let students know that the next activity will take place outside. Prepare students for the outdoors and gather materials for the Dirty Observations Lab activity. Give students the Dirty Observations Lab directions (S-7-7-2_Dirty Observations Lab.doc).

Dirty Observations Lab

Take the class outside and divide the class into teams. Each team should choose a site to observe. Assist students as they insert the four wooden sticks into the ground to form a 1-meter by 1-meter square and wrap the string around them.

Have students observe closely what is within the boundaries of the ecosystem. Then have students dig up a sample of soil from the ecosystem and place it in a previously prepared observation box. The observation box will consist of a box top lined with plastic wrap. Students should put the dirt inside the observation box and take it indoors for further investigation.

Have students answer the Dirty Observations Lab questions and conclusion together in their groups.

After students have answered the questions, discuss why there were variations in living and nonliving things observed or collected within the ecosystem.

Day 2

In preparation for the lesson, read through the Aquatic Ecosystem Lab procedure (S-7-7-2_Aquatic Ecosystem Lab.doc). Obtain pond water from a local source or order it from a biological supply company. Set up microscope stations before class, if possible.

Note: For the Aquatic Ecosystem Lab, students should have prior experience using the microscope, slides, and cover slips. If students are unfamiliar with preparing wet mount slides, provide them with the How to Prepare a Wet Mount Slide procedure (S-7-7-2_How to Prepare a Wet Mount Slide.doc).

Prior to conducting the lab, give students the Microorganisms article to read (S-7-7-2_Microorganisms.doc). Discuss the following questions with students:

• “In which of Earth’s ecosystems do microorganisms live?” (all of them)
• “Can you identify some microorganisms you are already familiar with?” (Answers will vary.)
• “When are microorganisms helpful to plants?” (They are helpful when they act as decomposers and recycle nutrients into the soil, and when they provide nitrogen for plants.)
• “When are microorganisms harmful to other organisms?” (They are harmful when they invade host organisms and cause disease.)

Hand out to students copies of the Aquatic Ecosystems Lab directions (S-7-7-2_Aquatic Ecosystem Lab.doc) and How to Prepare a Wet Mount Slide (S-7-7-2_How to Prepare a Wet Mount Slide.doc). Provide each group with a sample of pond water. Students should put the water on a slide, cover it with a cover slip, and observe the drops under the microscope. Students should record their findings in their science notebooks, such as an illustration and written description of what they saw. Students should also answer the question in their science notebooks: “How do microorganisms support ecological balance?” Have each group present its findings to the rest of the class. Discuss what was similar and different among all of the groups’ findings.

After wrapping up the Aquatic Ecosystems Lab with the class, say to students, “Now that we have discussed ecology and have learned about the different components of ecosystems, let’s discuss symbiosis. Symbiosis means living together. There are three different types of symbiotic relationships: parasitism, commensalism, and mutualism.”

Hand out a copy of the Symbiosis worksheet to each student (S-7-7-2_Symbiosis Worksheet and KEY.doc). If you have a document camera, project the worksheet on your board. Work with students to fill in the graphic organizer. Have students use their background information and vocabulary to familiarize themselves with the concept of symbiosis and examples of these relationships.

Hand out the Examples of Symbiosis worksheet (S-7-7-2_Examples of Symbiosis and KEY.doc). Allow students time to work independently in order to complete the worksheet. Go over the correct answers with the class.

After reviewing the correct answers with the class, project the following Web site on the board: www.saburchill.com/ans02/chapters/chap019.html. If the Internet is not accessible, hand out a copy of “The Ecosystem: An Inter-acting Community” (S-7-7-2_The Ecosystem.doc), and the Competition–Guided Reading Questions (S-7-7-2_Guided Reading Questions and KEY.doc). After students complete the worksheet, go over the correct answers.

As a closing activity, hand out three sticky notes to each student. Say to students, “I would like you to write down three interesting facts you learned about symbiosis. Once you finish writing three facts, post them on the board.” Give students about five minutes to brainstorm. After students have posted their facts on the board, go over several of them with the class. Also, use this time to answer any remaining questions.

Extension:

• For students who may need an opportunity for additional learning, describe examples of symbiotic relationships that humans can be a part of (e.g., ticks biting us, microorganisms in our intestines, having pets) and ask students to classify them as parasitism, mutualism, or commensalism. Then have students practice by thinking of one more example of each kind of symbiosis.
• Students can complete the Fan-N-Pick Kagan Cooperative Learning Structure verbal activity. Give students index cards with vocabulary terms and/or ecology phrases. Working in small groups, have students pick a card and define the word or phrase on the index card.

o   Fan-N-Pick (an activity for teambuilding, mastery, thinking, communication): Students play a card game to respond to questions.

1.   Student 1 holds the question cards in a fan and says, “Pick a card, any card!”

2.   Student 2 picks a card, reads the question out loud, and allows five seconds of think time.

3.   Student 3 answers the question.

4.   Student 4 restates the answer.

a.  For right or wrong answers, Student 4 checks if correct and then either praises or coaches.

b.  For a higher-level thinking activity when questions have no right or wrong answers, Student 4 does not check for correctness, but praises and paraphrases the thinking that went into the answer.

5.   Students rotate roles clockwise for each new round.

Source: http://edweb.sdsu.edu/People/tkopcha/fall2007/mathed502/kagan_strats.pdf

• Students who might be going beyond the standards can investigate how probiotics in foods such as yogurt may improve human health. Have students prepare a one-minute advertisement for a new food product with probiotics and present it to the class. Suggested Web sites:

o   http://en.wikipedia.org/wiki/Probiotic

o   www.mayoclinic.com/health/probiotics/AN00389