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S3E1. Obtain, evaluate, and communicate information about the physical attributes of rocks and soils.
a. Ask questions and analyze data to classify rocks by their physical attributes (color, texture ,luster, and hardness) using simple tests.
(Clarification statement: Moh’s scale should be studied at this level. Cleavage, streak and the classification of rocks as sedimentary, igneous, and metamorphic are studied in sixth grade.)
Success Criteria
- I can observe rocks carefully using my senses.
- I can describe the color of a rock.
- I can describe the texture of a rock.
- I can identify whether a rock is dull or shiny.
- I can test the hardness of a rock.
- I can compare rocks using their physical properties.
- I can sort rocks into groups based on observations.
- I can ask questions about rocks and their properties.
- I can record data from rock investigations.
- I can explain how I classified rocks using evidence.
Rocks are natural materials made of minerals. Scientists classify rocks by observing their physical properties. In third grade, students focus on observable characteristics rather than learning rock formation types.
Physical Attributes of Rocks
Color
Rocks come in many colors including gray, black, brown, red, white, and pink. Color alone is not enough to identify a rock, but it is an important observation.
Texture
Texture describes how a rock feels:
- Smooth
- Rough
- Grainy
- Bumpy
Students can use touch and hand lenses to examine textures.
Luster
Luster describes how light reflects from a rock’s surface.
- Shiny rocks reflect more light
- Dull rocks reflect less light
At this level, students only need simple descriptions such as shiny or dull.
Hardness
Hardness is how resistant a rock is to scratching. Students should explore the Mohs Hardness Scale in simplified form.
Mohs Hardness Scale
The Mohs scale ranks minerals from softest to hardest:
1-10
Examples students may use:
- Fingernail
- Penny
- Paper clip
- Nail
Students compare whether one object can scratch another material. The focus is on simple testing and comparison rather than memorizing the full scale.
Investigation Focus
Students should:
- Ask questions about rock properties
- Observe and compare rocks
- Conduct simple hardness tests
- Record data in charts or tables
- Group rocks based on evidence
Students are NOT expected to learn:
- Igneous, sedimentary, or metamorphic rock types
- Cleavage or streak testing
- Complex mineral identification
- Rock – a natural solid material found on Earth
- Physical Attribute – a characteristic that can be observed
- Color – the appearance of a rock
- Texture – how a rock feels
- Luster – how shiny or dull a rock appears
- Hardness – how difficult a rock is to scratch
- Mohs Scale – a scale used to compare hardness
- Classify – to sort into groups based on properties
- Observation – information gathered using the senses
- Investigation – a scientific test or activity
- Data – information collected during an investigation
- Evidence – facts or observations used to explain ideas
Knows
What students should understand
Students know that:
- Rocks have observable physical properties.
- Rocks can differ in color, texture, luster, and hardness.
- Scientists classify rocks using observations and tests.
- Hardness can be tested by scratching materials.
- The Mohs scale compares hardness.
- Data collected during investigations helps scientists organize information.
- Rocks can be grouped based on similar properties.
Shows
What students should be able to do
Students can:
- Observing and describing rocks
- Identifying color, texture, luster, and hardness
- Conducting simple hardness tests
- Comparing rocks using observations
- Recording investigation data in charts or journals
- Sorting rocks into groups based on properties
- Asking questions during investigations
- Explaining classifications using evidence
- Using scientific vocabulary correctly in discussion and writing