☀️ ☁️ 💧 🌧️
Lesson

The Water Cycle

A puddle dries up after the rain and seems to vanish. Yet the oceans never empty and the rain keeps coming back. The same water has been moving around Earth for billions of years.

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Driving Question
What keeps Earth's water moving in an endless cycle?
🔬 Learning Science Focus 🔍 Phenomenon First 🧠 Chunked Content 🖼️ Dual Coding ✅ Retrieval Practice 📊 Systems & Cycles

What You'll Be Able to Do

By the end of this lesson, you will be able to:

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I can describe how water cycles through the ocean, air, land, and living things.
7.MS-ESS2-4
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I can explain how energy from the Sun drives evaporation and transpiration.
7.MS-ESS2-4
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I can explain how the force of gravity drives precipitation, runoff, and infiltration.
7.MS-ESS2-4
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I can model the water cycle and explain why Earth's water is never used up.
7.MS-ESS2-4
📚 Instructional Design
Why this section exists
  • State what students will be able to do.
  • Set a clear target before content begins.
Cognitive science
  • Goal setting
  • Advance organizers
Bloom's / DOK
  • Understand to Analyze
  • DOK 1 to 3
Accessibility considerations
  • 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.

📚 Instructional Design
Why this section exists
  • Front-load the terms students will meet.
  • Lower the language barrier before reading.
Cognitive science
  • Pre-teaching vocabulary
  • Reduced extraneous load
Bloom's / DOK
  • Remember to Understand
  • DOK 1
Accessibility considerations
  • 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.

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Real World Phenomenon

Water That Never Runs Out

Earth has had about the same amount of water for billions of years. No new water is being made, and almost none escapes into space. The water in your glass may once have fallen as rain on a dinosaur. So if water is never created or destroyed, how does it keep moving from the ocean to the sky to the land and back again?

Ocean Evaporation Condensation Precipitation
The same water travels from ocean to sky to land and back, over and over again.
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Make a prediction: If no new water is ever made, what keeps the same water moving around Earth instead of just sitting still in the ocean?
Here's the big idea

The best answer is B. Two forces never stop working on Earth's water. Energy from the Sun heats water and lifts it into the air, and gravity pulls water back down to the land and ocean. Together they push the same water through an endless loop called the water cycle. To see how, we have to follow a single drop on its journey.

Where we're headed: First we'll meet the two forces that move all of Earth's water. Then we'll follow a drop as it rises into the sky, forms clouds, falls as rain, and travels back across the land to the ocean.
📚 Instructional Design
Why this section exists
  • Anchor the lesson in a familiar phenomenon: a drying puddle.
  • Raise a question students will want answered.
Cognitive science
  • Curiosity gap
  • Phenomenon-based learning
Bloom's / DOK
  • Understand
  • DOK 2
Accessibility considerations
  • Concrete, familiar examples
  • Short framing text
  • Visual anchor

What Moves the Water

The water cycle is not random. Every step is powered by one of two forces working together: energy from the Sun and the force of gravity.

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An Endless Loop

Water on Earth is never used up. It simply changes state and changes place. A drop can be liquid in the ocean, a gas in the air, and a liquid again when it falls as rain.

Because the same water keeps cycling, we call it the water cycle. Two forces keep the loop turning, and they push in opposite directions.

☀️ Powered by the Sun
  • The Sun's heat lifts water up into the air
  • Drives evaporation from oceans, lakes, and soil
  • Drives transpiration from plants
⚖️ Powered by Gravity
  • Gravity pulls water down toward the ground
  • Drives precipitation falling from clouds
  • Drives runoff and infiltration across and into the land
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The key pattern: The Sun pushes water up, and gravity pulls water down. The endless tug between these two forces is what keeps water cycling through the ocean, the air, and the land.
📚 Instructional Design
Why this section exists
  • Establish the two driving forces before naming each step.
  • Ground the whole cycle in cause and effect.
Cognitive science
  • Advance organizer
  • Cause-and-effect modeling
  • Comparison and contrast (Sun vs gravity)
Bloom's / DOK
  • Understand to Apply
  • DOK 2
Accessibility considerations
  • Two short, parallel comparison cards
  • Plain "up vs down" framing
  • Key terms in bold

Follow a Drop of Water

A single drop travels through four main stages, again and again. Click a stage to follow the drop on its journey.

1 2 3 4
1 · Evaporation & Transpirationwater rises
2 · Condensationclouds form
3 · Precipitationwater falls
4 · Collectionrunoff & groundwater
Click a stage
Start at the ocean →
Each stage moves water to a new place and often changes its state. Click any stage to follow the drop and see which force is at work.
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It never ends: After collection, the Sun's heat lifts the water up again and the loop repeats. There is no true start or finish to the water cycle.
📚 Instructional Design
Why this section exists
  • Give a whole-cycle map before studying each step.
  • Show the loop has no beginning or end.
Cognitive science
  • Advance organizer
  • Dual coding with the interactive diagram
  • Pattern recognition (up, across, down, return)
Bloom's / DOK
  • Remember to Understand
  • DOK 1 to 2
Accessibility considerations
  • Click to reveal each stage, no hover
  • Labeled diagram paired with text
  • Numbered, ordered stages

Lifted Into the Sky

The journey begins when the Sun's energy lifts water off Earth's surface. This happens in two ways, one from water and one from plants.

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From Liquid to Vapor

Energy from the Sun heats up liquid water and changes it into water vapor, an invisible gas. Water that leaves Earth's oceans, rivers, lakes, and wet soil rises up into the atmosphere.

Key idea: Evaporation

Evaporation is the process in which the Sun's heat turns liquid water into water vapor that rises into the air. Most of the water in the cycle evaporates from the oceans, because oceans cover most of the planet.

Key idea: Transpiration

Plants move water too. Transpiration is the process of evaporation from inside of plant cells into the atmosphere. Plants pull water up from the soil through their roots, and that water exits as vapor through tiny openings in their leaves.

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Same idea, two sources: Evaporation and transpiration both add water vapor to the air using the Sun's energy. One comes from open water and soil, the other from living plants.
📚 Instructional Design
Why this section exists
  • Explain the Sun-driven inputs to the cycle.
  • Connect a physical process to a biological one.
Cognitive science
  • Chunking related processes together
  • Cause-and-effect (heat to state change)
  • Linking to living systems
Bloom's / DOK
  • Understand to Apply
  • DOK 2
Accessibility considerations
  • Key terms defined in place
  • Short paragraphs
  • Plain comparison of the two sources

Clouds and Rain

Once water vapor is high in the atmosphere, the air around it is cold. That cold is what turns vapor back into the water we can see.

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Cooling Makes Clouds

As water vapor rises up into the atmosphere, it starts to cool and become liquid again. When a large amount of water vapor cools and joins together, the result is cloud formation.

Key idea: Condensation

Condensation is the process in which rising water vapor cools and turns back into tiny liquid droplets. Billions of these droplets together form a cloud. Condensation is the opposite of evaporation: vapor becomes liquid instead of liquid becoming vapor.

Key idea: Precipitation

When the water in the clouds gets too heavy to stay up, gravity pulls it back to Earth. Precipitation is water that falls back to the surface as rain, snow, sleet, or hail.

⚖️
Gravity takes over: Up to this point the Sun did the work, lifting water into the sky. Now gravity does the work, pulling the heavy droplets back down to the land and ocean.
📚 Instructional Design
Why this section exists
  • Explain how vapor becomes clouds and rain.
  • Mark the handoff from the Sun to gravity.
Cognitive science
  • Contrast (condensation vs evaporation)
  • Cause-and-effect (cooling to droplets)
  • Linking force to motion
Bloom's / DOK
  • Understand to Analyze
  • DOK 2
Accessibility considerations
  • Key terms defined in place
  • Opposite processes stated plainly
  • Short paragraphs

Back Across the Ground

Once precipitation lands, gravity keeps pulling it downhill and downward. The water takes two different paths back toward the ocean.

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Flowing Across the Surface

When rain falls on the land, some of it flows across the surface. Water that collects in rivers, streams, and oceans this way is called runoff. Gravity pulls this water steadily downhill until it reaches a larger body of water.

Key idea: Runoff

Runoff is precipitation that flows over the land and collects in streams, rivers, and the ocean. It is the surface path that returns water to the sea.

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Soaking Into the Ground

Not all of the water stays on top. Some of it soaks into the soil and rock below.

Key idea: Infiltration

Infiltration happens when precipitation soaks down into the soil and rocks. The water that collects underground forms pockets of groundwater. Most groundwater slowly moves through the ground and eventually returns to the ocean.

Two paths, one destination: Whether water runs off the surface or infiltrates the ground, gravity keeps moving it toward the ocean. There the Sun can lift it back into the air, and the cycle begins again.
📚 Instructional Design
Why this section exists
  • Explain the two land paths that close the loop.
  • Return the drop to the ocean to restart the cycle.
Cognitive science
  • Comparison (surface vs underground path)
  • Cause-and-effect (gravity to flow)
  • Closure of the cycle schema
Bloom's / DOK
  • Understand to Analyze
  • DOK 2
Accessibility considerations
  • Key terms defined in place
  • Two clearly separated paths
  • 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.

Quick Recall · 1 of 3
Just a quick brain check. Not graded.
The Sun heats the ocean and water rises into the air as an invisible gas. What is this process?
Quick Recall · 2 of 3
Just a quick brain check. Not graded.
Water vapor high in the sky cools and turns back into tiny droplets that form clouds. What is this?
Quick Recall · 3 of 3
Just a quick brain check. Not graded.
Rain falls on a hill and flows downhill into a river. What is this moving surface water called?
📚 Instructional Design
Why this section exists
  • Strengthen memory through retrieval before the wrap-up.
  • Surface misconceptions early.
Cognitive science
  • Retrieval practice
  • Generation effect
  • Productive struggle
Bloom's / DOK
  • Understand to Apply
  • DOK 1 to 2
Accessibility considerations
  • Ungraded and low stakes
  • Immediate feedback
  • Short tasks reduce load

One Endless Loop

You started with a question: what keeps the same water moving around Earth? Now you can trace the whole loop, step by step.

The Sun Lifts Water Up
Energy from the Sun powers evaporation and transpiration.
The Sun's heat turns liquid water into water vapor from oceans, soil, and plants. The vapor rises into the atmosphere.
The Sky Cools It Down
Cooling causes condensation, and gravity causes precipitation.
High up, vapor cools and condenses into clouds. When the droplets grow heavy, gravity pulls them down as rain or snow.
Gravity Returns It
Runoff and infiltration carry water back to the ocean.
Water flows across the land as runoff or soaks in as groundwater. Both return to the ocean, where the Sun can lift it again.
The full loop:
Sun heats the water Evaporation and transpiration Condensation forms clouds Gravity pulls down precipitation Runoff and infiltration return it
Earth's water is never created or destroyed. The same water moves endlessly between the ocean, the air, the land, and living things, driven by the Sun's energy and the force of gravity. That is why the puddle vanished but the water never ran out.
📚 Instructional Design
Why this section exists
  • Tie the steps into one cause-and-effect loop.
  • Answer the opening question directly.
Cognitive science
  • Schema building
  • Elaboration
  • Coherent narrative
Bloom's / DOK
  • Understand to Analyze
  • DOK 3
Accessibility considerations
  • Step-by-step beats
  • 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.

Your score will not be sent Your score will be sent to your teacher
0 / 10 selected
🧠 Show Your Thinking

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.

In one or two sentences, trace how a single drop of water leaves the ocean, rises into the sky, and travels back across the land to the ocean again. Name the two forces that move it, the Sun and gravity, and the processes they drive. Use the word back.

One strong way to say it The Sun's heat evaporates a drop from the ocean into invisible water vapor that rises into the air. High up it cools and condenses into a cloud, and when the droplets grow heavy, gravity pulls them down as precipitation. The water then runs off the surface or soaks in as groundwater and flows back to the ocean, where the Sun can lift it again. The same water is never used up, so the loop repeats.
📚 Instructional Design
Why this section exists
  • End the lesson with the student constructing the cycle in their own words, not selecting it.
  • Give the one place where the student generates rather than clicks.
Cognitive science
  • Generation effect and self-explanation
  • Systems thinking: tracing one drop through the whole loop
  • Self-check reveal for comparison, ungraded
Bloom's / DOK
  • Analyze to Evaluate
  • DOK 3
Accessibility considerations
  • Sentence-length response, not an essay
  • Keyword scaffold ("back")
  • Model answer to compare against

🔍 The Question You Came In With You started this lesson asking: "What keeps Earth's water moving in an endless cycle?" If you can trace the Sun lifting water up, clouds forming, gravity pulling rain down, and water returning to the ocean, you have answered it.
📚 Instructional Design
Why this section exists
  • Check understanding against the lesson goals.
  • Give students and teachers a clear signal.
Cognitive science
  • Retrieval practice
  • Feedback loops
Bloom's / DOK
  • Understand to Apply
  • DOK 1 to 2
Accessibility considerations
  • 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, the water-cycle steps powered by the sun and pulled by gravity. More investigations, simulations, and challenges are coming soon.

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More Coming Soon
The lesson is just the beginning. More investigations, simulations, and challenges are coming soon.
Coming Soon
📚 Instructional Design
Why this section exists
  • Offer pathways beyond the core lesson.
  • Signal that learning continues past the quiz.
Cognitive science
  • Interest-driven extension
  • Transfer to new contexts
Bloom's / DOK
  • Apply to Analyze
  • DOK 2 to 3
Accessibility considerations
  • Optional and self-paced
  • Clear labels for what is available
  • No penalty for skipping