Ecology Lesson 8: Population Growth and Succession

Title of Lesson: Population Growth and Succession

Situation: 9^th grade Biology 1, 35 high school students of mixed gender

Time: 85 minute block schedule

Concept or conceptual understanding (listed as a sentence or 2):

Students will learn about population growth and succession. They will be introduced to many examples illustrating factors that affect both.

Real world connections (Relevancy):

Population growth affects our society and each individual in it. Factors that affect both population growth (human or otherwise) can be influenced by humans and can have direct effects on us (eg. disease, pest outbreaks, crop kills, natural disasters).

AZ standards: (include grade level and text):

AZ Strand 1, Concept 1: Formulate predictions, questions, or hypotheses based on observations. Evaluate appropriate resources. POs 1-4

AZ Strand 1, Concept 2: Design and conduct controlled investigations. POs 1, 5

AZ Strand 1, Concept 3: Evaluate experimental design, analyze data to explain results and propose further investigations. POs 6

AZ Strand 1, Concept 4: Communicate results of investigations. POs 2-4

AZ Strand 2, Concept 1: Identify individual, cultural, and technological contributions to scientific knowledge, PO 3.

AZ  Strand 3, Concept 1:Describe the interactions between human populations, natural hazards, and the environment. POs 1-5

AZ Strand 3, Concept 2: Develop viable solutions to a need or a problem. POs 4, 5

AZ Strand 3, Concept 3. Analyze factors that affect human populations. POs 1-3

AZ Strand 4, Concept 3: Analyze the relationships among various organisms and their environment. POs 1-3

Strand 4, Concept 4: Understand the scientific principles and processes involved in biological evolution. PO 4, 5

Incorporation of inquiry:

Students will incorporate inquiry via simulations and laboratory activities. 

Behavior objectives:

Objective 1: Students will synthesize previous ecology lessons with the current lesson to: a) define and illustrate population growth and succession, and b) address factors that affect population growth and succession.

Objective 2. Students will conduct and interpret results of a laboratory experiment.

Prior knowledge necessary:

Students will build on knowledge from previous ecology lessons. Students will also require knowledge of sterile techniques and microscopy.

Identify possible student preconceptions:

Succession only happens following a disturbance.

Population growth is linear.

Population growth is only influenced by births and deaths.

Materials:

Lab notebooks, pencils, model lily pads (sticky notes), cut outs of predators, prey, plant and invader, lima beans, pipettes, 100-ml beaker, cover slips, microscope slides, 10-ml graduated cylinder, methylene blue stain, 4 test tubes, aluminum foil, microscope, test-tube rack, before/after photos. Supplemental materials: worksheets for lily pad and invasive species activity, lab protocol and worksheet for bacteria lab, power point.

Safety:

Students will practice standard safe practices. There is nothing inherently dangerous in any of these activities.

Lesson Description:

• Bellwork: What is a population? Can it keep growing indefinitely?
• Follow-up: Discussion of why populations cannot grow indefinitely.
• Cover population growth (immigration, emigration, birth death), exponential and logistic growth, carrying capacity, population crashes, limiting factors, density depend and independent factors, S curve, J curve with power point.
• Lily pad lab – model exponential growth by adding “lilly pads” to fill half the student’s desk. How many more days will it take to fill the desk? Graphing exercises will illustrate the J curve. Relate back to real problems with lily pad growth in China.
• Students will culture bacteria (see lab handout). Measurements will be taken for the next 6 days (5 minutes per class).
• Use invasive species activity (rabbits in Australia) to solidify concepts from Lessons 5 and 6 and population density. Each student (in a group) will represent one of the following: primary producer, native herbivore, predator, invasive herbivore with rules for each generation (see supplemental material).
• Cover reading “combination” graphs with students (p. 442).
• Lecture over Succession (primary/secondary succession, pioneer species, disturbance).
• Use photos of Ponderosa pine forest from 1800s and today to look at how communities change in time. Talk about the factors that lead to these changes.

Assessment:

Worksheet from lab activities, observation, question and answer.

References:

Lessons have been adapted from:

• McDougal/Littell Biology 2008 by Stephen Nowicki
• Pretice/Hall Biology 2008 by Ken Miller and Joe Levine
• http://naturalsciences.sdsu.edu/classes/lab2.7/lab2.7.html