1. Figure 25.1 shows a basic food web and illustrates the balance of the ecosystem and trophic levels.

2. List out and review the terms from Section 7.9, covering elements in a food web.

3. The sun's existence, more specifically, the reception of sunlight, is an absolute necessity for life on earth, and atmospheric changes that affect how much sunlight reaches the earth should be monitored and described.

4. Pictures of other galaxies or solar systems could be shown to emphasize the possibility that the earth may not represent the only ecosystem in the universe.

1. Show Figure 25.2 and discuss wind patterns on the earth.

1. Figure 25.3 illustrates ocean currents and the Gulf Stream.

2. Figure 25.4 illustrates overturn in the ocean.

1. Show nice color photos or videos of ocean communities.

2. Figures 25.5, 25.6, and 25.7 show factors that define oceanic communities, pelagic zones, and abyssopelagic zones.

3. Figure 25.8 shows abyssal communities around hydrothermal vents.

4. Shows Figures 25.9 and 25.10 and discuss neritic communities.

5. Figure 25.11 shows an estuary; discussion of these areas could include incorporation of current events related to their destruction or the threat thereof.

6. Figures 25.12 and 25.13 show the types of coral reefs.

7. Figure 25.14 shows other inhabitants of a reef community.

8. Videos of varying reef communities and other marine communities from different parts of the world could be shown to further enhance presentations of these topics.

9. In the lab, set up a marine aquarium and stock it with a variety of organisms; invertebrate animals are especially interesting and not difficult to keep.

1. Figure 25.15 shows different kinds of freshwater plants.

2. Figure 25.16 shows the complicated food web of a freshwater habitat, including the three zones of habitats that exist.

3. Show photos of a lake in summer and one in winter (with ice covering) in discussing overturn.

4. Figure 25.17 shows plants typically found in bogs.

5. Figure 25.18 shows a typical marsh.

6. Figure 25.19 shows a typical swamp.

1. Figure 25.21 shows how land topography can affect the distribution of precipitation.

1. For each of the major biomes, show the text figures or other photos to illustrate the individual features of the biomes.

2. The use of videos can show the interactions among plants, animals, and the physical environment in various biomes; these also add movement and sound to the illustrations.

1. Figure 25.31 shows how climate determines biomes.

2. List out the six major climate types and their associated vegetation.

1. Show photos of soil types, including Figure 25.34, a cross section across various types.

2. To illustrate how soil type dictates regional agriculture, show fields of food crops like corn growing in black soil, cotton growing in clay soil, root vegetables growing in sandy soil.

1. Figures 25.36 and 25.37 show biogeographic realms and their representative animal groups; show these and discuss convergent or parallel evolution.

1. Show Figure 25.38 in discussing tectonic plates.

2. Show photographs of faults (e.g. the Great Glen fault in Scotland).

3. Show a map of the tectonic plates superimposed on the continents, and discuss the San Andreas fault, earthquakes, and plate tectonics.

4. Figure 25.39 or a similar map showing the continents that are thought to have existed in the past is usually dramatic.