Lesson 2 of 10
Objective: Students will be able to describe characteristics that ecologists use to describe populations and make predictions on how said populations may change in the future.
This lesson is a follow up to the Population Sampling lesson and covers ways that ecologists describe populations. This lesson content will be explored in more depth in the predicting human population change and human geography lessons and continue in the second part of the Population Ecology lesson covering how populations grow.
The lesson essentially consists of two parts:
1. A pre-class textbook reading and homework assignment focused on close reading techniques, critical-thinking questions, and content vocabulary development.
2. An in class presentation that provides supplementary examples to review the concepts and vocabulary from the chapter along with a class discussion seeking to draw students into more critical examination of the topic at hand and assist in their ability to connect the concepts to their personal experiences.
The textbook reading comes from Environmental Science: Your World, Your Turn by Jay Withgott.
If you do not have that particular textbook, I would recommend finding a similar chapter or chapters and modifying the lesson accordingly.
Alternately, the powerpoint attached to the Direct Instruction section covers most of the same concepts and vocabulary as the chapter. If you have a shorter class period, you may want to skip the reading assignment and assign the discussion questions as homework. You could then hold the class discussion on the following day.
In my case, I assign the textbook reading on the meeting previous to this lesson. In that way, students will have already covered the concepts on their own and the powerpoint presentation will be less of a lecture and more of an opportunity for students to ask questions and clarify their understanding.
Connection to Standard:
In this lesson, students will prepare for class by reading and determining the central idea of a text, establish familiarity with relevant scientific vocabulary, and then draw evidence from the text to support arguments and opinions presented as part of their participation in a group discussion.
Like I mentioned above, I assign the textbook reading as a homework assignment to be completed upon arrival to this class period. The powerpoint presentation is then more of a review and an opportunity for students to ask questions.
Wondering WHY I use lectures as a pedagogical strategy? Watch this video.
Wondering HOW I use the Powerpoint to differentiate instruction? Watch this video.
Wondering why I choose to have a reading assignment AND a lecture on the same content? Read this rationale.
Wondering how you might use this lesson's resources if you don't plan on presenting a lecture? Read this reflection.
When class begins, I ask students to get their homework out and first give them about 10 minutes to discuss the critical thinking questions with their group members. During this time, I walk around and put a stamp on completed homework and answer any questions that students bring up. If students bring up a good question or insightful comment, I ask them to please remember to bring that up in the larger class discussion to follow the presentation.
Affording this time before the presentation allows students to "field test" their answers with a smaller group, increasing their confidence to participate in the larger discussion. Also, because the discussion is graded by groups, it allows the ideas of individual members to influence the thinking of their peers which may lead to greater insights or even new questions. Finally, while I walk around, I listen to the nature of student discussions and get a better sense of what kinds of questions may be floating around the room, allowing me to emphasize certain aspects of the lesson or offer more detailed examples to scaffold the instruction.
After I have stamped all the homework assignments, I distribute the note sheet that accompanies the presentation. As I've mentioned in previous lessons, offering students a note sheet provides a readymade study guide for later and allows students to focus on their thoughts and the concepts being discussed as opposed to focusing all of their attention on copying down copies amounts of notes.
Please Note: I find it important to really do thorough checks for understanding on a few points in this lecture:
1. The sampling discussed on slide 3 is a callback to the "Mark and Recapture" activity they have recently completed. Although the method described in the text of the presentation is just extrapolation, I ask students to contrast that with the mark and recapture method and have them discuss quickly which method might be more accurate. Answers will vary, but I'm really just checking here to see if they understand how there are different methods to estimate a population.
2. For the slides regarding population density, this can be the basis for a fruitful discussion on the comparative costs and benefits of high and low population density. I found this a great discussion point for my students because my school is located in the Koreatown and Westlake neighborhoods of Los Angeles, two of the most densely populated zip codes in the entire nation outside of New York City. For my students, it was interesting for them to talk about what they liked and didn't like about their neighborhood's density. This also provided a forum for some students to share their own experiences traveling to more remote regions. One student described his trip to Texas as, "a whole lot of nothing... seriously, it's just EMPTY there". Depending on the community your school is located in, it might be telling to have this discussion and allow students to share their own experiences with density.
3. The age structure diagrams at the end of the presentation become critically important in the Predicting Human Population Growth lesson. I have included images of some typical age structure diagram shapes and an opportunity to for students to compare and contrast Angola with Ukraine, but you may want to include more examples or at least reference back to this notesheet when your class does the Predicting Human Population Growth lesson.
Following the presentation, I let students know that we will wrap up by having a class discussion to review the concepts of the lesson. Again, depending on your class length, it may be preferable to have this follow-up discussion on the following day.
The discussion protocol for this lesson:
all groups are required to participate in the discussion and will receive a “participation” grade for the day
groups with more than one member that participate will receive a higher participation grade
groups that participate more frequently will receive a higher grade
These criteria make the group collectively responsible for their grade and accountable to each other. If no one in the group participates, the group as a whole will receive a failing grade. If only one member of the group participates, regardless of how often, the group can’t receive any grade higher than a C.
To keep track of participation, I begin by making a map of the class with the group tables labeled by group name. Since there are four students at each table, as a student from a particular group participates, I make a tally mark in the position of that student in their group. In this way, I can tally how often the group participates, which members are participating, and how often. To determine "average" participation, I add up all tally marks and divide by the number of groups, rounding down. I then use this rubric to determine their participation grades.
If you'd prefer to not give a grade for participation in discussions, see this reflection where I discuss the conditions that arose that allowed me to not to grade for participation but still have meaningful discussions with broad participation.
See this discussion guide for specific strategies for this discussion, but I would bring your attention to two key points from the guide that may affect how you lead the discussion:
1. Regarding the question of which type of population distribution humans have, the main idea in asking the question here is for students to understand that humans have a clumped population distribution (rather than random or uniform) as our settlements are clumped near resources such as waterways, farmland, agreeable climate, etc. This concept is important to understanding how certain large countries can have very low population densities (because density is calculated by considering individuals and the total area, not just the populated area) and still seem "crowded" in many areas.
2. On the question of which ages are pre-reproductive, reproductive, and post-reproductive, this presents a great opportunity to have a discussion of not only the biology of human reproduction, but the cultural aspects of reproduction. On the one hand, this question could discuss differences between nations, but it could potentially be even more fruitful to have the discussion about differences between cultural groups in the United States. As I mention in the discussion guide, as long as the tone is kept respectful, this could be a very interesting discussion. This topic is brought up again in the Demographic Transition lesson and both lessons present great opportunities for students to share their personal experiences.
See this reflection for more thoughts on leading a discussions on a potentially divisive topic.