Grade Level: K-8

ACF Lesson Plan: Coal Flowers: A Historic Craft


Students observe the process of crystallization in the making of coal flowers, a historic craft among coal mining families.

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Students will:

  1. re-create the historic process of making coal flowers,
  2. make observations about the crystallization process that occurs during this craft, and
  3. describe the role that the practice of making coal flowers played in coal mining families.

National Standards:

National Science Education Standards (NSES)

  • Science as Inquiry, K-4, 5-8
    • Abilities necessary to do scientific inquiry
  • Physical Science, 5-8
    • Properties of matter and changes in properties of matter

National Council for the Social Studies (NCSS) Standards

Time Needed:

Two 45-minute class periods


  • Shallow glass bowls (one for each team of students)
  • Coal or any rock will do (several pieces per work team)
  • Twigs and/or toothpicks
  • Small pieces of cloth, paper, or string
  • Paper towels
  • Glue
  • Mixing bowls or cups
  • 6 tbsp salt per work team
  • 6 tbsp laundry bluing per work team*
  • 6 tbsp water per work team
  • 1 tbsp ammonia per work team
  • Food coloring
  • Thermometer to measure air temperature
  • Coal Flowers Worksheet for each team

*If the grocery or hardware store does not carry laundry bluing, check with a pharmacy. It can also be ordered through many women’s magazines or purchased over the Internet at

Discussion Questions:

  • What do you know about crystals?
  • Where have you seen them?
  • How are they formed?
  • Have you ever heard of “coal flowers”? If so, do you know when and how they were made?

Background Information:

Begin by explaining to students that the making of coal flowers is a historic craft that was practiced by coal mining families in the late 1800s and early 1900s. When mining families had little money to buy decorations or purchase toys, they used common household products and coal to make beautiful crystal flowers. It was entertaining to watch the crystal flowers grow, because the changes took place in a relatively short period of time. Coal flowers were sometimes used as Christmas decorations because they resemble snowflakes.


  1. In this activity, students will make their own coal flowers. Explain that the coal actually plays no chemical role in the creation of the crystals and is no more critical an ingredient than the toothpicks used. In addition, students will use food coloring to enhance the beauty of their coal flowers, although original coal flowers were made without this additive.

  2. Divide the class into manageable work teams of two to four students each. Give each group the necessary materials. Display the following procedures for each group to follow in making their coal flowers:
      • a.  In the shallow bowl, place several small lumps of coal.
      • b.  Arrange any combination of twigs, toothpicks, paper, cloth, or string with the coal. Use glue to hold the pieces to the coal if desired.
      • c.  In a separate bowl or cup, mix the salt, laundry bluing, water, and ammonia.
      • d.  Pour this mixture over the coal mound.
      • e.  Sprinkle dots of food coloring over the mound.

  3. Distribute copies of the Coal Flowers Worksheet. Have students immediately complete the first three questions, documenting the air temperature according to the thermometer. If possible, document the crystal formation on an hourly basis (either on the Coal Flowers Worksheet or in a science journal), noting change in size, shape, and color or color vibrancy of the crystals. Complete the rest of the Coal Flowers Worksheet once the flowers are fully formed, which should take no more than eight hours.

  4. Have different groups place their coal activity to different predetermined locations such as:
      • a.  under heat lamps
      • b.  in the refrigerator
      • c.  in a window
      • d.  on a table
    Make sure the students document the air temperatures and contrast the timing of the process at different temperatures, as well as the color vibrancy of the crystals.


Place the experiment in its historical context by discussing why this activity might be a natural one for coal mining families in the late 1800s and early 1900s. Either photograph the crystals or have the students draw them and explain in their own words how they made the flowers. They should describe the process as well as the changes they noticed over time.


Have students graph the different temperature findings for comparison purposes.


Challenge higher-level students to research and report on the actual chemical reactions that caused the crystallization on the coal.

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