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K–12 teaching and learning · from the UNC School of Education

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Learning outcomes

Students will learn:

  • how to differentiate between intrusive and extrusive igneous rocks by texture.
  • why some extrusive rocks have holes.
  • why rock, both intrusive and extrusive, varies in color.

Teacher planning

Time required for lesson

1 hour

Materials/resources

  • Large table
  • hot plate and non-stick frying pan or electric griddle
  • spatula
  • ingredients for pancake batter
  • dark chocolate powder or syrup
  • mixing containers
  • paper plates, napkins or paper towels
  • Samples of rock-forming minerals such as quartz, orthoclase and plagioclase feldspar, muscovite and biotite mica, amphibole hornblende, or pyroxene
  • Samples of intrusive and extrusive rocks such as gabbro, diotite, granite, pumice, scoria, obsidian, or rhyolite.

Pre-activities

  • Students should have a basic understanding of the rock-forming minerals and their general shades of color (light, medium, dark).
  • Students should know how igneous rocks form and how they are divided into extrusive and intrusive categories by differences in texture due to cooling rates.
  • Students should have an understanding of mineral formation. Fast cooling creates small or no crystals and slow cooling results in large crystals.

Activities

  1. The instructor should arrange a demonstration table before the lesson with the minerals, rocks, and pancake-making materials. The rocks should be separated and labeled by name as either extrusive or intrusive. The minerals should be separated into light, medium, or dark shades of color.
  2. The table should be placed so that students can gather around the table for a close up view. The instructor can begin the lesson by reviewing the rock forming minerals and their general shade of color. Next, there should be an explanation concerning how the lesson will model how different textures and colors occur in igneous rocks.
  3. The instructor should designate a volunteer to be the chef to mix up a batch of pancake batter. The batter should be divided into two separate containers. One of the mixtures should be colored dark by adding some form of chocolate.
  4. The griddle should be pre-heated on LOW heat. Place a small amount of both batters on the cooker and allow them to cook slowly. During the cooking process be sure to have students note the gas holes and how they heal themselves.
  5. After both pancakes have cooked, they should be placed on a plate and displayed on the table with the intrusive rocks.
  6. The griddle should be turned on high. Both light and dark batters should again be placed on the cooker, but this time they will be cooked fast. Have students note how with fast cooking, the holes remain! After cooking, display these pancakes next to the intrusive rocks.
  7. Ask the students the following questions:
    • What two factors caused the fast and slow cooked pancakes to look different? (cooking rate and ingredients)
    • What causes holes to develop in pancakes? (gases escaping)
  8. At this point have students return to their seats for the assessment. As students work on the questions, the instructor should use the remaining batter to cook pancakes that could be cut into small pieces and distributed to the class as a reward for satisfactory completion of the assessment. Be sure to supply syrup and plenty of napkins or paper towels!

Assessment

Directions: Answer the following questions which relates pancake formation to igneous rock formation.

  1. What word can be substituted for cooking when relating pancakes to igneous rocks? (cooling)
  2. What did the pancake batter represent? (lava or magma)
  3. What did the dark colored batter represent? (dark colored lava or magma)
  4. What did the chocolate represent? (dark colored minerals)
  5. What did the slow cooked pancakes represent? (slow cooled intrusive rocks)
  6. What did the fast cooked pancakes represent? (fast cooled extrusive rocks)
  7. What causes holes in some igneous rocks like pumice and scoria? (fast cooling with gases escaping as the lava cools into rock)
  8. Why do some igneous rocks contain the exact same minerals, but differ in looks? (cooling rates and percent of mineral composition)
  9. Name an igneous rock from the samples displayed that contains light colored minerals, but appears dark in color. (Obsidian—light can penetrate the edges of broken pieces)
  10. List other similarities you can think of between the cooking of pancakes and the cooling of igneous rocks.

North Carolina curriculum alignment

Science (2005)

Grade 6

  • Goal 3: The learner will build an understanding of the geological cycles, forces, processes, and agents which shape the lithosphere.
    • Objective 3.04: Describe the processes which form and the uses of earth materials.
      • Rock cycle.
      • Minerals.
      • Characteristics of rocks.
      • Economic use of rocks and minerals.
      • Value of gems and precious metals.
      • Common gems, minerals, precious metals and rocks found in N.C.