1. Earth Materials Investigation 1
Mock Rocks
Part 3 – Observing Crystals

2. Science Jobs
Manager – this person will make sure that all members are on task
Reporter – this person will report the results of their groups work, you may need to take notes
Materials getter – this person will get materials
Materials collector – this person will return materials

3. Investigation 1, Part 1 Review
Rocks have many properties, including shape, size, color, and texture
Geologists use rock properties to help identify different rocks
Some dimensions of rocks can be measured and compared

4. Investigation 1 – Part 2 Review
The difference between rocks and minerals
Rocks are made up of different ingredients, minerals of only one.
How the minerals in a rock can be separated
Some minerals can be separated and identified by breaking the rock apart.
Some rock materials separate and settle when mixed with water.
Some minerals dissolve when mixed with water.

5. Investigation 1 – Part 2 Review
A rock is an earth material made up of different ingredients called minerals.
A mineral is an ingredient of rocks that cannot be broken down any further. We do not mean that it can’t be hit with a hammer and broken into smaller piece. We mean that no matter how many pieces you break it into, it is still the same material.

6. What We Will Learn
What is left behind when the water evaporates from our dishes.
How to identify the material that is left behind.

7. Materials FOSS tray with evaporation dishes 4 hand lenses
4 copies of the Crystal Identification Key – Student Sheet No. 12

8. What We Will Do Material getters – take your materials to your group.
Use your hand lenses to carefully observe what is left in the evaporation dishes.
Draw a detailed picture of what you see.
Discuss what you see in your groups.
Reporters share your group’s findings.
What did your groups find that were alike and different?

9. Crystals
The little squares in the dishes are called crystals. A crystal is a solid form of a material that can be identified by its characteristic shape or pattern.
What do you think these crystals might be?
Use the Crystal Identification Key to compare and identify the crystals in the dish.

10. Discussion
Discuss how the crystals got from the mock rock to the evaporation dish.
Share.
When water was added to the mock rock material, the salt dissolved in the water.
When the liquid from the vial was placed in the dish, the dissolved salt went in with the water.
The water evaporated into the air, leaving salt crystals in the dish.

11. Earth Materials Booklet Mock Rocks – Page 6 – 7
Explain what you see in your evaporation dish and how it got there.
Refer to pages 2 – 6 in your booklet to make a list of the mock rock ingredients on page 7.
How is a mock rock like a real rock? Discuss in your groups and then record your answer.

12. Vocabulary
Crystal – the solid form of a material that can be identified by its shape or pattern
evaporation – when the liquid water becomes water vapor

13. What We Have Learned The mock rocks contained salt.
By putting the liquid from the vials in the evaporation dish and letting the liquid evaporate we can use a crystal identification key to identify the substance that was dissolved in the water.

14. Science Story
Read “Postcards from the Ledge”