Show the children the sheer abundance of ocean water and habitat that exists on the planet. Explain that over 70 percent of the Earth's surface is covered with water. Use a standard globe to compare the area that is land to the area that is water. Relay the fact that even the Earth's tallest mountains are not as deep as some parts of the ocean. In this respect, the students can grasp what an enormous role the ocean can play in the climate and in the diverse ecosystems that inhabit it.
Breach the well-known subject of global warming and explain the ocean's role in absorbing heat. At the beginning of the lecture, place a small bowl of water outside the classroom in warm weather and in direct sunlight. As you explain the following concept, the water will warm, illustrating your point. Explain that as the earth warms from natural and man-made processes, the ocean does the "heavy lifting" of absorbing the majority of the heat. Explain that the top layers of the ocean absorb more heat than the entire earth's atmosphere. In this respect, the students can grasp the concept of the ocean as being a major player in controlling climactic change.
Explain the role of ocean currents in maintaining healthy weather patterns. Use a diagram of oceanic currents illustrated with red and blue for hot and cold currents. Using a globe, explain that the greatest amount of heat is absorbed at the equator because it is closest to the sun. Holding the diagram next to the globe, show how ocean currents dissipate this heat toward the poles, letting proper evaporation and condensation to take place. Teach that healthy ocean currents help keep weather patterns sustainable for human kind.