HS-ESS2-5: Investigating How Water Shapes Rock
Also called NGSS HS-ESS2-5 · Topic: Earth's Systems · Earth and Space Science
The Official Wording
Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.
Clarification statement: Emphasis is on mechanical and chemical investigations with water and a variety of solid materials to provide the evidence for connections between the hydrologic cycle and system interactions commonly known as the rock cycle. Examples of mechanical investigations include stream transportation and deposition using a stream table, erosion using variations in soil moisture content, or frost wedging by the expansion of water as it freezes. Examples of chemical investigations include chemical weathering and recrystallization (by testing the solubility of different materials) or melt generation (by examining how water lowers the melting temperature of most solids).
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-ESS2-5 Means in Plain English
Students plan and run their own investigations of water's properties and how they change rock and land. They might measure how freezing water expands and splits stone, how running water carries and drops sediment, or how water dissolves some minerals.
No formal limit is set, but the investigation should tie water's behavior to the rock cycle and the water cycle. It builds on weathering and erosion from MS-ESS2-2 and supports models of landform change in HS-ESS2-1.
HS-ESS2-5 I Can Statements
- I can plan a fair test of how water affects rock.
- I can explain why freezing water can split rock.
- I can connect water's properties to weathering and erosion.
HS-ESS2-5 Worked Example
A multi-day ice wedging test using plaster blocks and a classroom freezer.
Can water freezing inside a crack break solid material?
Set It Up: Six plaster of Paris blocks each with a drilled hole, water, a freezer, a ruler, and a 100 mL graduated cylinder.
- Leave 100 mL of water in the cylinder in the freezer overnight and read the new volume.About 109 mL of ice
- Fill the holes in three blocks with water and leave three dry as controls.3 wet, 3 dry
- Chill all six overnight until solid, then thaw them the next day, topping up the water, for five cycles.Same cold, same times
- Measure and sketch the cracks in every block after each cycle.Wet blocks crack and the cracks widen, dry blocks stay whole
Only the water-filled blocks cracked, and their cracks grew with each cycle of icing and thawing.
Why it works: Water expands about 9 percent when it turns to ice, so ice in a crack pushes outward with great force, and repeated cycles pry the material apart.
Common Mistakes with HS-ESS2-5
Thinking water shrinks when it freezes
“Ice takes up less space, like most solids.”
Try this: Water is unusual: its molecules lock into an open pattern as ice, so the same mass takes up about 9 percent more space.
Skipping a control
Freezing only wet blocks and blaming the cold for the cracks
Try this: Freeze matching dry blocks alongside the wet ones, so any cracks can be traced to the water rather than to cold alone.
Seeing weathering as only physical
“Water just breaks rocks into pieces.”
Try this: Water also dissolves minerals like calcite, carving caves in limestone, and it lowers the melting point of rock deep underground, helping form magma.
Where HS-ESS2-5 Fits
Practice HS-ESS2-5
Quick Check
- Why is frost wedging common where temperatures swing above and below freezing?
- 100 mL of water freezes. About what volume of ice forms?
- How does water help form caves in limestone?