Engage the students with Dr. Art's three "big questions."
Still using the Water Cycle Model as the focus of the discussion, pose these three big questions (from Dr. Art's Guide to Planet Earth) and encourage thoughtful responses by way of class discussion, small group discussion, and/or written response.
What are the parts of the system?
Check to see if all students labeled evaporation, precipitation, and runoff correctly, and then encourage more thinking and responses about the many other parts of the water cycle.
How does the system function as a whole?
In the water cycle, there is no start or stop point. The sun heats up the ocean and the water evaporates. The water collects in the atmosphere and forms clouds. This water in the atmosphere ends up falling back to the earth. We call this precipitation. When the rain or snow falls on hills and mountains, it ends up flowing downward into streams and rivers. It eventually flows into the oceans. This is called runoff. Then, the sun heats up the ocean and the cycle continues.
How is the system itself part of a larger system?
Students discuss with a partner how the water cycle affects or is affected by other systems. Some examples include: transportation system, waste treatment system, agriculture system, energy system, weather system.