MS-ESS2-4: Modeling the Water Cycle
Also called NGSS MS-ESS2-4 · Topic: Earth's Systems · Earth and Space Science
The Official Wording
Develop a model to describe the cycling of water through Earth's systems driven by energy from the sun and the force of gravity.
Clarification statement: Emphasis is on the ways water changes its state as it moves through the multiple pathways of the hydrologic cycle. Examples of models can be conceptual or physical.
Assessment boundary: A quantitative understanding of the latent heats of vaporization and fusion is not assessed.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-ESS2-4 Means in Plain English
Middle schoolers build a model of how water moves through oceans, air, land, ice and living things. They show water changing state as it evaporates, condenses into clouds, falls as rain or snow, and flows downhill, powered by sunlight and pulled by gravity.
Students describe the energy involved in words, without calculating how much heat each change of state absorbs or releases. It builds on where water is found on Earth (5-ESS2-2) and leads to weather patterns (MS-ESS2-5) and climate (MS-ESS2-6).
MS-ESS2-4 I Can Statements
- I can trace a drop of water through several paths in the cycle.
- I can explain how sunlight and gravity keep water moving.
- I can name the change of state at each step.
MS-ESS2-4 Worked Example
A model water cycle built in a bowl, with a lamp as the sun and ice as cold air.
Where does evaporated water go, and does it carry what was dissolved in it?
Set It Up: A large clear bowl with 2 cm of warm water tinted with food coloring, a small empty cup in the center, plastic wrap, a bag of ice cubes and a desk lamp.
- Stretch plastic wrap over the bowl and set the bag of ice on top, right above the cup.Wrap dips toward the cup
- Shine the lamp on the bowl for 30 minutes.Fog forms on the underside of the wrap
- Watch the droplets under the ice.Droplets grow, slide to the low point and drip
- Remove the wrap and look in the cup.A little water in the cup
- Compare its color with the water in the bowl.Cup water clear, bowl water still colored
Water evaporated, condensed under the cold wrap and dripped into the cup clear, leaving the coloring behind in the bowl.
Why it works: Energy from the lamp turned liquid water into vapor, cooling turned it back to liquid, and gravity pulled the drops down, just as sunlight and gravity drive the real cycle.
Common Mistakes with MS-ESS2-4
Thinking clouds are water vapor
“Clouds are made of steam or water vapor.”
Try this: Water vapor is an invisible gas. Clouds are tiny liquid droplets or ice crystals that formed when the vapor cooled and condensed.
Drawing one simple loop
A circle of ocean, cloud, rain, ocean, and nothing else
Try this: Add other paths, like water soaking into groundwater, freezing in glaciers or passing through plants, which can hold it for very different times.
Forgetting gravity
Arrows for evaporation and rain but nothing for rivers
Try this: Gravity pulls rain and snow down and moves water downhill in rivers and underground, so label it along with the sun's energy.
Where MS-ESS2-4 Fits
Practice MS-ESS2-4
Quick Check
- What provides the energy that evaporates water from the ocean?
- Why are drops on a cold glass of juice part of the same process that makes clouds?
- Ocean water is salty but rain is not. Why?