This lesson will introduce your students to the concept of how populations of organisms within ecosystems are supported and sometimes limited by the availability of resources and abiotic factors
CA State Standards – Grade 6: 5e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition
The students will demonstrate understanding that:
An organism's habitat consists of resources such as food, shelter, water, and a space to live.
The availability of these resources affects the number of organisms that an ecosystem can support.
Other factors such as climate, location, and human intervention can affect the availability of resources.
Area large enough for students to run, "Oh Deer" graph, and a pen for graphing.
Habitat and population.
Green plants are the foundation of the energy flow in most ecosystems, because they are capable of producing their own food by photosynthesis. Thus, they are the "producers" and the origin of food chains. Using sunlight and the process of photosynthesis, plants can convert carbon dioxide and water into sugar and oxygen. A food chain describes how this chemical energy, in the form of food and nutrients, is passed from organism to organism.
When consumers eat a producer, the consumer gains some of the food energy from that producer. When a consumer eats another consumer, again food energy and nutrients are passed from consumer to consumer. Thus, energy and matter are transferred in food from organism to organism. Plants are eaten by primary consumers or herbivores. Secondary consumers or carnivores eat herbivores. Tertiary consumers or top-level predators eat carnivores. Omnivores are consumers that can eat both producers and consumers. Energy is transferred from organisms to the physical environment through heat loss. Carbon as carbon dioxide in the air is exchanged between organisms and the physical environment through respiration. Water is also exchanged.
A "population" is a term for the total number of animals of the same species that live in a certain geographical area. A population of animals typically interacts with each other in an ongoing basis. For example, the Kings River Deer herd is a population of deer that live in the Kings River drainage. The number of individuals in a population is a constant changing number depending upon many biotic and abiotic factors, such as the availability of food and water, predators, disease, etc.
Tell the students that they are going to play a game called "Oh Deer!" It is a game about habitats. Habitats include resources an organism needs in order to survive – food, water, shelter and space. (Space includes room to move and grow and air to breathe.)
- Mark a base line at each end of the playing area. Have students stand on one baseline. This is the habitat line, and the students are now habitat. Teach them the symbols for food: hands on stomach; water: hands over mouth; and shelter: hands over the head, like a roof. Explain that the area in which the game is played will symbolize space, the fourth key element of habitat.
- Ask 6 to 8 students to volunteer to be deer. Send the students who will play the role of deer to the other baseline.
- Explain the rules by demonstrating with one student from the deer line and one student from the habitat line.
- "I will call 'Turn Away.'" The deer and habitat players will turn away from each other.
- "Pick your symbol." The deer and the habitat players each make a habitat symbol – food, water, or shelter.
- They must hold this symbol and not change it during the round being played.
- "Turn around and deer may go on the count of three." Deer and habitat players face each other. They must hold their symbols. Deer walk, not run, across playing area to tag someone on the habitat line who has the same symbol. Deer who successfully tag the habitat, they are seeking "survive" and "reproduce." They escort their habitat player to the deer line, and both will be deer in the next round of play. Deer who did not successfully tag the habitat they were seeking, die. They fall to the ground to decompose and become part of the habitat. These students will join the habitat line and become habitat players in the next round of play.
- During a round of play, habitat players remain on their line. Only the deer players move.
- No changing symbols during a round of play.
- A deer player may select one, and only one, habitat player per round.
- Tell the students you will graph the deer population over the next 10 years – 1 round equals 1 year.
- Play the game. Graph the population at the end of each round/year.
- Gather to analyze the graph. Connect dots on the graph into a line for greater visibility.
- For assessment or additional practice, have students complete the worksheet, Lesson 3 Illustration A.
An additional worksheet for "Oh Deer" is available for download in pdf format.
Adapted from: Project WILD, Western Regional Environmental Education Council, 1986.
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