The Water Cycle
A puddle dries up after the rain and seems to vanish. Where does its water go? Follow water as it moves among the air, land, oceans, and living things, or stays stored along the way.
What You'll Be Able to Do
By the end of this lesson, you will be able to:
- Set a goal of explaining a journey and an alternative within a closed Earth water system.
- Set a clear target before content begins.
- Goal setting
- Advance organizers
- Understand to Explain
- DOK 1 to 2; evaluate the student model separately
- Plain "I can" statements
- Standard code shown for reference
- Short, scannable cards
Words You'll Meet
Choose a card to see what each word means.
- Distinguish invisible water vapor from cloud droplets and ice crystals.
- Lower the language barrier before reading.
- Pre-teaching vocabulary
- Reduced extraneous load
- Remember to Understand
- DOK 1
- One card open at a time
- Click to reveal, no hover
- Plain, short definitions
The Puddle That Disappeared
After a rainstorm, puddles sit on the sidewalk. A few hours later they are gone, with no drain in sight. The water did not disappear. It moved, and it is still moving.
Water Within a Closed System
Earth is a closed system for water. Water does not leave the system or get added to it as part of the water cycle. Instead, it moves among reservoirs (places that store water) within Earth and changes location and state. A closed system does not mean one closed-loop pathway. How could the puddle's water move to another reservoir?
The best answer is B. Solar energy supplies much of the energy for evaporation: liquid water changes to invisible vapor. Gravity pulls precipitation downward and helps water flow downhill. These are different roles: the Sun is an energy source, and gravity is a force. Water follows many pathways and can remain stored along the way.
- Anchor the lesson in a familiar phenomenon: a drying puddle.
- Check that closed system is not interpreted as one closed-loop pathway.
- Curiosity gap
- Phenomenon-based learning
- Understand
- DOK 2
- Concrete, familiar examples
- Short framing text
- Visual anchor
What Moves the Water
Solar energy and gravity play different roles in the water cycle. Energy can help water change state; gravity is a force that affects its motion.
Earth is a closed system for water. Water moves among reservoirs and can stay stored in oceans, lakes, rivers, soil, groundwater, snow and ice, the atmosphere, and living things. A lake can lose liquid water by evaporation or gain it from rain and streams.
We call this connected movement and storage the water cycle. Water need not visit every reservoir or return to the ocean before moving again. Global recycling does not mean usable water is equally available everywhere at all times.
- The Sun supplies energy for much evaporation
- Supplies energy for evaporation from oceans, lakes, rivers, and wet soil
- Supports evaporation inside leaves during transpiration
- Gravity pulls water down toward the ground
- Drives precipitation falling from clouds
- Helps runoff flow downhill and water move through the ground
- Distinguish solar energy (energy source) from gravity (force).
- Gravity acts throughout; it does not switch on after condensation.
- Advance organizer
- Cause-and-effect modeling
- Comparison and contrast (Sun vs gravity)
- Understand to Apply
- DOK 2
- Two short, parallel comparison cards
- Plain energy-source and force distinction
- Key terms in bold
Explore Possible Water Pathways
Explore four groups of processes in any order. They are choices within a larger system, not four required stages for every drop. A journey may include storage and branch into different routes.
- Use these process groups as examples within a larger system.
- Choosing a process is exploration, not evidence of developing a model.
- Advance organizer
- Dual coding with the interactive diagram
- Compare alternative pathways and storage
- Remember to Understand
- DOK 1 to 2
- Click to reveal each process group, no hover
- Labeled diagram paired with text
- Choices can be explored in any order
Water Becomes Invisible Vapor
Water can enter the atmosphere from exposed wet surfaces and from plants. In both cases, liquid water changes into invisible water vapor.
Liquid water can change into water vapor, an invisible gas. Evaporation happens at exposed water surfaces, including oceans, rivers, lakes, and wet soil. Solar energy supplies much of the energy for evaporation in Earth's water cycle.
Evaporation is liquid water changing into invisible water vapor. It does not require boiling or direct sunlight. Movement upward in the air is not the state change itself. Most evaporation in the global water cycle occurs over the oceans, which cover most of the planet.
Plants move water too. They absorb water through their roots, and water moves through the plant. During transpiration, some water evaporates inside leaves and exits as vapor through tiny openings in the leaves.
- Explain transfers to the atmosphere within the closed system.
- Trace roots to leaves to vapor; evaporation does not require boiling or direct sunlight.
- Chunking related processes together
- Cause-and-effect (heat to state change)
- Linking to living systems
- Understand to Apply
- DOK 2
- Key terms defined in place
- Short paragraphs
- Plain comparison of the two sources
Clouds and Rain
When moist air cools enough, some invisible water vapor can become tiny liquid droplets. Clouds contain droplets and/or ice crystals, not visible water vapor.
Moist air can cool enough for some water vapor to condense into tiny liquid droplets. These droplets can form clouds. Clouds may also contain ice crystals, or both droplets and ice crystals.
Condensation is water vapor changing into liquid droplets when moist air cools enough. It is the opposite of evaporation: vapor becomes liquid instead of liquid becoming vapor. Cloud formation and falling precipitation are different processes.
Cloud droplets and/or ice particles can grow large enough to fall as precipitation. Gravity pulls them downward. Precipitation reaches land and ocean as rain, snow, sleet, or hail. Not all clouds produce precipitation.
- Explain how vapor becomes clouds and rain.
- Check that students separate condensation from precipitation; not every cloud produces precipitation.
- Contrast (condensation vs evaporation)
- Cause-and-effect (cooling to droplets)
- Linking force to motion
- Understand to Analyze
- DOK 2
- Key terms defined in place
- Opposite processes stated plainly
- Short paragraphs
Water on and Under the Ground
Water on land may flow across the surface, enter the ground, evaporate, or remain stored. Snow and ice can store water until melting lets it follow another pathway, such as runoff.
When rain falls on a hillside, some water flows downhill across the surface into streams and rivers. This is runoff. Gravity helps this surface water flow toward lower places.
Runoff is water flowing across the land surface. It may enter streams and lakes, collect temporarily, or infiltrate along the way. Surface flow and infiltration are connected pathways, not permanently separate tracks.
Not all of the water stays on top. Some of it soaks into the soil and rock below.
Infiltration is water entering the ground. Some infiltrated water stays in soil and can be taken up by roots or evaporate. Some moves deeper; entering the ground does not instantly make all water groundwater.
Groundwater occupies saturated pores and fractures in soil and rock: spaces filled with water. It can remain stored or move through those spaces, connecting with springs, streams, lakes, and oceans.
- Distinguish infiltration, soil water, and groundwater storage and flow.
- Groundwater fills saturated pores and fractures, not giant underground caverns.
- Comparison (surface vs underground path)
- Cause-and-effect (gravity to flow)
- Connections among surface water, soil, plants, and groundwater
- Understand to Analyze
- DOK 2
- Key terms defined in place
- Connected paths and storage described plainly
- Short paragraphs
Brain Check
Three quick questions before we put it all together. These are not graded. Pulling answers from memory now will help them stick.
- Strengthen memory through retrieval before the wrap-up.
- Surface misconceptions early.
- Retrieval practice
- Generation effect
- Productive struggle
- Understand to Apply
- DOK 1 to 2
- Ungraded and low stakes
- Immediate feedback
- Short tasks reduce load
One System, Many Pathways
Return to the drying puddle. Its water can become invisible vapor while staying within Earth. Use the processes below to explain a possible journey, including a place it could stay stored.
- Connect processes and storage without requiring an ocean return.
- Answer the opening question directly.
- Schema building
- Elaboration
- Coherent narrative
- Understand and Explain
- DOK 2; reading this summary is not a model-building performance
- Related ideas in short groups
- Plain causal language
- Builds on prior sections
Check Your Understanding
Ten questions covering everything you explored, from evaporation to groundwater. Answer every question, then submit.
Scientists don't just know the answer. They explain their thinking.
Write your own explanation first. Then submit your work to compare your thinking with a model answer.
Build a word model in 3–4 sentences. Explain why Earth is a closed system for water. Describe one possible journey with a state change and a place water could stay stored; include an alternative pathway from one reservoir. Explain the different roles of solar energy and gravity.
- Look for a closed-system boundary, a journey and alternative, state change, storage, and distinct energy/force roles.
- One route alone does not demonstrate understanding of multiple pathways.
- Generation effect and self-explanation
- Systems thinking: explain one possible journey and another route
- Self-check reveal for comparison, ungraded
- Apply and Explain
- DOK 2; deeper reasoning depends on the student response
- Short word model in 3–4 sentences
- Prompt names the model features to include
- Model answer to compare against
- Check understanding against the lesson goals.
- The score measures selected concepts; review the ungraded word model for connected reasoning.
- Retrieval practice
- Feedback loops
- Understand to Apply
- DOK 1 to 2
- Answer explanations provided
- Practice and classroom modes
- Plausible, evenly placed options
More Learning
The lesson is just the beginning. Dig deeper into evaporation, condensation, and precipitation, processes within a system of connected reservoirs. Explain how solar energy and gravity play different roles. More investigations, simulations, and challenges are coming soon.
- Offer pathways beyond the core lesson.
- Signal that learning continues past the quiz.
- Interest-driven extension
- Transfer to new contexts
- Apply to Analyze
- Depth depends on the follow-up task; clicking a link is not evidence of mastery
- Optional and self-paced
- Clear labels for what is available
- No penalty for skipping
Connections
Water can remain stored. When it moves, it can reshape the land it touches.