Unit C: Earth, Our Home

Why do rocks have different colors?

1. Get Set to Explore

Vocabulary

  • mineral: A nonliving thing found in nature.
  • rock: A nonliving thing made of one or more minerals.

Building Background

  • Review the definitions of the vocabulary words. Write the definitions on the board. You may wish to refer to the pictures on Student Edition pages, C14–15 for examples of both minerals and rocks.
  • Lead children on a brief rock-and-mineral hunt in or around your school. For each rock and mineral children find, ask them to name the color or colors that they notice.
  • Present the Discover! question: Why do rocks have different colors? Let children predict the answer. If you want to give them a hint, refer back to the definition of the word rock and to the different minerals they found on the rock and mineral hunt or to other experiences children have had examining rocks and minerals. Write children's answers on the board.

2. Guide the Exploration

  • Tell children to launch the Discover! Simulation and to listen closely to the question and the directions.
  • You may wish to demonstrate how to drag the magnifying glass over one of the rocks. Let children talk about how the rock looks different when they view it through the magnifying glass. Elicit the idea that the tiny grains and specks that make up the rock look bigger under the magnifying glass.
  • Give children the KWL Chart to use to describe the different rocks they examine in this simulation. Prompt them to record the name of the rock, its colors, and anything else about it they find interesting.
  • Make a KWL Chart on the board and ask children to share what they observed and learned about each of the three rock samples. Use the chart to record what children say about the different rocks.

3. Review/Assess

  • Go over Step 3's Wrap-Up text with the class. Make sure that children understand that the tiny specks of color and grains of material that they find inside the rocks are minerals. Point out that rocks look different because they are made up of different combinations of minerals.
  • Replay the simulation's descriptions of the different rocks. Work with the class to list different minerals mentioned along with the color or colors of each mineral.
  • Challenge children with the Extension question. You may wish to ask them to imagine that they could create their own special rock. Ask: What colors would your special rock be? What minerals could you use to give your rock these colors? Let children pair up to answer the questions. Remind them to look at the list on the board to figure out the colors of different minerals. Children's answers may incorporate any of the following minerals and others:
    • white–limestone, chalk, feldspar, quartz (clear)
    • red–hematite, feldspar, quartz (clear)
    • pink–quartz (clear); green–serpentine, feldspar
    • blue–diopside; yellow–feldspar
    • black–diopside, mica (shiny)

If time permits, present children with the following questions:

  • Inquiry Skill Classify Look at real rocks or pictures of rocks. Based on the colors you see, what minerals do you think are in the rocks? Try to classify your rocks based on the minerals you think they contain. Answer: Classification will depend on the types of rocks or pictures of rocks you provide the children. Accept any classification children defend by correctly referring to colors and minerals.
  • Critical Thinking Evaluate Which rock do you think is the prettiest? Which mineral or minerals give this rock its beauty? Answer: Answers will vary. Accept any answer that children defend by correctly referring to minerals and their colors.

4. Reaching All Learners

English Language Learners

Before assigning the simulation, explain that the simulation includes some difficult names of minerals. Write some of these on the board and pronounce them for children. (You can refer to the list given above for the different minerals mentioned.) Reassure children that they do not need to learn how to write these words, and they do not need to memorize the color of these minerals. Explain that you are introducing and pronouncing these words to make it easier for them to understand the simulation.