Students who demonstrate understanding can: Develop a model to describe the cycling of Earth's materials and the flow of energy that drives this process.
Clarification statement: Emphasis is on the processes of melting, crystallization, weathering, deformation, and sedimentation, which act together to form minerals and rocks through the cycling of Earth's materials.
Assessment boundary: Assessment does not include the identification and naming of minerals.
Official wording from the Next Generation Science Standards (NGSS Lead States, 2013). NGSS is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the NGSS were involved in the production of this page, and they do not endorse it. View on nextgenscience.org
Rock that looks permanent is actually being recycled, just slowly. Students build a model showing how Earth's materials move between forms through melting, crystallization, weathering, deformation and sedimentation, and they identify the two energy sources that power the system: heat from Earth's interior, which melts and deforms rock, and energy from the sun, which drives the wind, water and ice that break rock down and move the pieces.
A good model is not a neat circle with arrows in one direction. Igneous rock can weather into sediment, be buried and squeezed into metamorphic rock, or be melted again without ever becoming sedimentary. Each arrow is a process, and each process needs a source of energy. Crystallization, for example, happens as magma or lava cools and loses thermal energy, while sedimentation depends on gravity pulling particles down in water or air.
Students do not need to identify or name minerals. The point is to explain the pathways and the energy flow that keeps the cycle going.
Students often think rock must go igneous, then sedimentary, then metamorphic. Any rock type can change into any other, and some steps can repeat.
Rocks change over very long times. A weathered gravestone or a crumbling sidewalk shows the process happening on a human time scale.
Metamorphic rock forms from heat and pressure without melting. If the rock melts, it becomes magma, and cooling produces igneous rock.
Internal heat drives melting and deformation, but the sun drives weathering and erosion through the water cycle and wind.
Explain, using the rock cycle, how a granite mountain could become a layer of sandstone and what energy drives each step.
Answer: The granite weathered into sand, the sand was eroded and deposited, and burial cemented it into sandstone; internal heat formed the granite, while solar energy and gravity drove weathering, erosion and deposition.
Start with real samples students can handle and ask for a possible history of each. Crayon shavings are a classic model: shaving represents weathering, pressing the shavings represents compaction, warming and pressing represents metamorphism, and melting and cooling represents igneous rock. Discuss where the model breaks down, such as time scales and actual temperatures.
Assessment items often give an incomplete rock cycle diagram to label, or ask students to name the energy source for a given process.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: A) Cooling and crystallization
When magma or lava loses thermal energy, minerals crystallize and igneous rock forms.
Answer: D) The sun
Solar energy drives wind and the water cycle, which break down and move rock.
Answer: C) By heat and pressure changing rock without melting it
Metamorphic rock forms when heat and pressure change existing rock while it stays solid.
Answer: sedimentary (also accepted: sedimentary rock)
Compaction and cementation of sediment produce sedimentary rock.
Answer: A) Any type of rock can change into any other type
There are many pathways; any rock can be weathered, transformed by heat and pressure, or melted.
Answer: gravity
Gravity causes particles carried by water or wind to settle out and form layers.
Make observations and/or measurements to provide evidence of the effects of weathering or the rate of erosion by water, ice, wind, or vegetation.
Develop a model to illustrate how Earth's internal and surface processes operate at different spatial and temporal scales to form continental and ocean-floor features.
A full lesson with slides, activities and an exit ticket on the rock cycle and earth's energy, pitched to grades 6-8 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on MS-ESS2-1 with an answer key, ready in about a minute.
Make a worksheet βTurn the rock cycle and earth's energy into a quiz students answer online that marks itself, with a class summary for you.
Build a test βNo. The assessment boundary excludes identifying and naming minerals. Students focus on processes and energy flow.
Melting, crystallization, weathering, deformation and sedimentation, and how they work together to form rocks and minerals.