There are basically three kinds of rock: sedimentary, metamorphic and igneous.
• Sedimentary rock forms when layers of dirt, clay, mud, rocks and sand squeeze together over a very long period time.
• Igneous rock forms from hot, molten rock after it cools.
• Metamorphic rock forms when high heat and pressure take igneous or sedimentary rock and squeezes them, over a very long period time, into new rock.
The goal of this simple activity is to closely observe and identify rock types using the attached key.
• Rock samples
• Hand lens
• White vinegar
• Paper towels
• Paper plates
1. Lay out one rock sample on each paper plate.
2. Have students examine one rock sample at a time using a hand lens.
3. Using the key, have students identify if each rock sample is sedimentary, metamorphic or igneous.
4. They can use an extra paper plate to do the vinegar sizzle test.
5. It may take several tries with each rock, where students will have to go back to the beginning and try again. This is part of the process and is good for developing their observational skills.
This process can be done at home any time. Encourage students to share this process with their parents and start a rock collection of their own.