Lisa Lanza
Manlius Pebble Hill
Biology (9th grade)
Host Teacher: Susan Loedel
Lesson Title:
How populations grow (16.1)
Lesson Objectives:
Students will be able to distinguish between the three patterns of dispersion within a population
SWBAT differentiate between r-strategists and K- strategists
Teaching Standards:
The Living Environment: Standard Four MST; Key Idea 1. Living things are both similar to and different from each other and nonliving things. Performance indicator: Explain how the diversity of populations within ecosystems relates to the stability of ecosystems.
Content / Concept overview
Distinguish between three patterns of dispersion in a population
Contrast exponential and logistical growth
Differentiate r-strategists and K-strategists
Key Terms:
Population
Population size
Population density
Dispersion
Population model
Exponential growth curve
Carrying capacity
Density dependent factor
Logistical model
Density independent factor
r-strategist
K-strategist
Instructional Order:
Teacher 10-15 minutesMap Population and resources National Geographic
The lesson will begin with a brief introduction and group discussion of a map of the world with population statistics and other information on world population (human). Students will gather around a large table with a map and talk about populations, population size human population statistics. Population density where most people are populated versus areas with few humans. We will talk about how they are dispersed on the map and why. Why are so many people located in the united states and very few people living in the Sahara of Africa? For example
Group discussion
3 Key features of populations:
Population density, population size and dispersion. / Students: Large Group Discussion
Students will examine the map and ask and answer questions:
How are the populations dispersed? (clumped, even and random)
How would population size affect a population’s ability to survive? (a small population)
Population density. How would a very remote and small population affect finding a mate?
*Small populations most likely to go extinct. Inbreeding, susceptible to natural disasters and diseases could wipe them out.
Where are most people found? Around water, resources
Where clusters of people not found?
Does the data on population surprise you? The people symbols, where would you expect to find the most people?
How about income, energy consumption, cropland or CO2?
Concept introduction: 15-20 minutes
Population models I will draw the three types on the board
Growth rate: Stage I
r(rate of growth)= birthrate- death rate
Stage II model: exponential growth curve
delta= rN
Use the stage 1 model to show r.
Exponential growth shows slow growth at first then increase very rapidly.
Stage III model: Logistical model
deltaN=rN (K-N)
K K(carrying capacity)
Logistic growth begins slowly then increases exponentially and finally stabilizes as the population reaches carrying capacity. / Students will take notes and ask questions about the model
Draw them and show current one of US.
Talk about factors on the map What do you think causes a spike in population on the human growth model? And which does it resemble? Stage II exponential growth curve.
Group discussion about the human population model. Does anyone know how fast the world’s population is growing per day? by200, 000 people a day.
In the next 35 years, 2.5 billion people will be added to the current population of 6 billion. Between 1980 and 2000 total world population grew from 4.4 billion to 6 billion. By 2015 another billion people will equal 7 billion.
Density dependent factors: i.e. food and water, waste disposal, and predation/disease. Dependent on how large a population
Density independent factors: weather and climate
See my notes for this section. / Can you think of any density dependent factors in nature or in humans?
Independent factors?
Group activity: 20 minutes
r-strategists and K-strategists
* Most species have evolved a strategy somewhere in between the two models. Compared to a continuum and r- and K strategists are at the two extremes. Some species change from one strategy to the other as their environment changes.
Break into groups to complete a worksheet on the two Growth strategies and we will discuss as a class. Advantages and disadvantages of each group.
Which strategist am I? Rapid population growth under ideal conditions, no parental care and a short life span. (r-strategist)
How would a K strategist differ?
(Slow pop. Growth, parental care and long life span)
What do the r and K refer to in these two types? (K- refers to the carrying capacity variable and r- refers to the growth rate variable r because this type shows such rapid growth.) / Students will work in groups completing the growth strategies worksheet.
Then we will have a group discussion and they will answer questions about the two groups.
Students will compare and contrast the two growth strategies comparing Graph’s, size of population, environment, reproduction, offspring, and examples.
Nasonia lab:
Students observed their Nasonia projects for the last time. Recording observations and continuing on with their analysis. They talked in their lab groups about the life cycle of both organisms. The flesh Fly and Nasonia / Students got into their Nasonia lab groups and finished observations on their projects. They discussed the life cycle of the parasitic wasp (Nasonia) and how it uses the larva of a flesh fly to feed its young. The students will finish the lab for homework.
Ticket out the door 5 Minutes
What did you learn today about populations that you thought was interesting?
What did you already know about populations that we talked about?
What did you find hard to understand about populations or population models or anything that you found confusing or did not understand? / Students will take out a scrap piece of paper and put their name on it. They will answer the three questions as their ticket out activity.
Reflection:
I used the ticket out the door activity during every lesson to understand if students are learning concepts. The ticket out the door gives me an idea of what they enjoyed about the lesson or did not understand. During this lesson students did not feel confident about population models. They felt the equations were confusing didn’t quite get K= carrying capacity and exactly what the graphs were showing. I am going to develop a power point handout with the graphs again. I think they feel responsible for the equations if I gave them numbers. However, I just wanted them to understand what it would look like if a population was rising or falling. I am including a copy of the notes I gave the students.
I felt the opening activity (map activity) went well it helped students visualize population features such as density, population size, and dispersion. We discussed other features of the map such as water resources, CO2 production, fresh water resources (Even a little geography review). I asked it any thing on the map was surprising to them. They replied they were interested to see we have less people than most continents but 3X as much CO2
Some other surprises too such as Oceania has so much fresh water supplies and few people.
The end of the lesson went well: students worked in groups using their textbooks to complete a worksheet on r/K strategist and put together their understanding of the population models carrying capacity and strategies of both groups. The students stayed in their groups and checked on their Nasonia lab. They completed their observations and finished the analysis part for homework. I had another fire drill during C block my largest class. The second time they have had a fire drill during biology. They had to finish the r/K worksheet for homework. (They started it but couldn’t finish it if we wanted to do the Nasonia finale)…