Chapter 12 Lesson 4, "How Materials Cycle Through Ecosystems"

Materials:

• Chapter 12 Vocabulary Review.

Objective:

• Students will describe how water cycles through ecosystems.
• Students will explain the roles of photosynthesis and cellular respiration in the carbon, oxygen, and water cycles.
• Students will describe how nitrogen cycles through ecosystems.
• Students will explain how cycles in ecosystems are linked to one another.

Anticipatory Set:* Think about the Earth as a spaceship. Everything we need and use comes from the earth. building materials, tools, food, if we run out of something there is no way we can get more. Pose the question, "Why is there still oxygen in the air if animals have been breathing it for millions of years?" Look for the word cycle in any of the responses and emphasize it. Compare and contrast the word cycle with the word circle. Introduce the students to the water cycle first. Have the students trace the snowflake as it is melting. Have them help develop a drawing of a simple water cycle on the overhead or on the chalkboard. Show the students some other pictures of water cycles and compare and contrast them as you explain them. (water cycle 1, water cycle 2,) Make sure and emphasize the words evaporate and condense in your explanation. What form of water do you first notice in the diagram? How else does water exist? Where does the water cycle begin?

Teacher Input:* Ask the students what other things move through the biosphere, in and out of ecosystems in cycles. As they name each explain them. (carbon cycle 1, carbon cycle 2; oxygen cycle 1, oxygen cycle 2, nitrogen cycle.)

These cycles are all linked in an ecosystem. Look at the pictures of photosynthesis and respiration and compare how they are linked to these cycles.

Guided Practice:* Show the students how the nitrogen cycle is controlled in agricultural fields. Call attention to the Technology Note on Page 322 then show this pictures as you discuss how farmers control nitrogen levels.

Use these pictures to explain.

Nitrogen is used by farmers in the form of anhydrous ammonia.	Most often and traditionally it is put on when tilling the soil in the spring.	This is what it looks like in the field.	This is what it looks like as it is going in under the soil.	Another way to put anhydrous ammonia in the soil is to do it at planting.

Some fields have patches where nitrogen is deficient and the whole field doesn't need a lot of nitrogen.	Some applicators are designed for putting on fertilizers after the crop has begun to grow. this piece of equipment has special sensors that tell how much to put on at different spots in the field.	The sensor in from sends a signal to the sprayer in back on how much nitrogen to put on.	Some farmers also use handheld sensors that they carry around the field and	This tractor has a satellite communication system that uses the sensors and a satellite to tell the farmer how much fertilizer to put on.	Here are the gauges in the cab that tell the farmer how much nitrogen to put on.

Independent Practice:* Students will read section 4 and complete the Chapter 12 Vocabulary Review.

Check for Understanding:* Students will take the quiz on lesson 4

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-9 Students will understand the transfers and transformations of matter and energy that link living things and their physical environment, fro molecules to ecosystems. (Flow of Matter and Energy)
• SCI A-14 Students will understand
  • the interdependence between living things and their environments:,
  • that the living environments consists of individuals, populations, and communities: and
  • that a small change in a portion of an environment may affect the entire environment (Interdependence);

• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and: