Edible rocks

         Igneous Rocks

Materials

1 12-ounce bag milk chocolate chips

1 12-ounce bag white chocolate chips

1 piece waxed paper (at least 18 x 24 inches/46 x 61 centimeters)

1 cookie sheet with sides

1 stirring spoon

heating device – microwave or double-boiler

microwave-safe bowl or double-boiler depending on heating method

rock samples from Unique Rock

D  What to Do:

1.       Review from Unique Rock that that the main way geologists classify rocks is by how they were formed. 

2.     Explain that igneous rocks are formed when melted rock, called magma, is forced up from the earth’s core through the earth’s surface and cools.  They are going to see a similar process when they make Edible Igneous Rocks.

3.     Place the white and milk chocolate chips in a bowl or pot.  Have the girls notice that there are individual pieces (chips), much like individual minerals in a rock.  Refer to rocks they have looked at in Unique Rock.

4.     Heat the chips until they melt.  Explain that this is similar to rocks melting in the high heat at the earth’s core.

5.     Mix well until all signs of individual chips is gone and the colors are completely blended.

6.     Show the children the bowl again.  Note that you can no longer see the individual chips and it is instead in a liquid mixed form.  This is similar to the liquid rock, called magma, in the earth’s core.

7.     Cover the cookie sheet with a sheet of wax paper.  As you pour the liquid chocolate onto the wax paper, tell the children that when there is a volcano the magma is forced through the earth’s surface and comes out as lava.  It then hardens as it cools and turns into igneous rock in the same way that the chocolate will harden as it cools.

8.     Set the chocolate aside to cool.  Caution everyone against touching the mixture, as it is very hot.

9.     Once the chocolate has cooled, break it up and notice that the new “rock” is made of the same ingredients, but is not like any of the original “rocks” which were melted and that none of these ingredients are visible anymore.  Eat and enjoy.

D  Helpful Hints

1.       Check for food allergies.

2.     Stir chips often and be careful not to burn the mixture.

3.     You can also sprinkle in some other kinds of chips (dark chocolate, butterscotch chips, peanut butter chips, marshmallows) in order to simulate the greater mixture of minerals in the magna and rocks.

4.     You can make a double boiler out of an electric hotpot of boiling water with a smaller saucepan sitting in the water.

5.     To speed the cooling process, put the mixture in the refrigerator for approximately 10 minutes.

D  Whys and Hows

          Igneous rocks are formed from melted rock that has cooled and hardened.  Rocks that are deep in the earth melt because of the high temperatures and the pressure.  The melted rock is called “magma.”  The magma is heated and forced up from the center of the earth through the earth’s crust.  Some of it comes out on the surface through a volcano as lava, and some of it stays underground where some will harden.  As it cools, the lava or magma hardens and turns into rock.  Therefore, The specific type of igneous rock formed depends on three things…how fast it cooled, where it cooled (outside of the earth’s surface, under the water, or under the earth’s surface) and what combination of chemicals was in the magma.  The slower a substance cools, the larger the crystals will be.  Thus, magma that cools more slowly, usually underground, will form larger crystals than those formed from the lava that is spewed out of a volcano and cooled rapidly.  Some examples of igneous rocks are granite (formed underground and cooled slowly, so there are visible crystals), obsidian (formed above the earth’s surface from lava hardened that hardened quickly), and pumice (formed from lava blasted out of a volcano into the air and cooled so fast that the gases were not able to escape, leaving lots of little holes in it).

Igneous Rocks: Igneous Mint Fudge

Concept: Igneous rock formation

Continued rise in temperature can eventually melt any rock until it is molten (called a magma). When the molten rock cools it forms an igneous rock. All three main types of rock (igneous, sedimentary, and metamorphic) can be melted to form magma.

Objective:

Students will be able to explain how igneous rocks form.

Materials:

• water
• 4 cups sugar
• 1¾ cups evaporated milk
• 1½ cups butter
• 12 oz package of chocolate mint wafers
• 16 oz package of marshmallows
• stove
• candy thermometer
• heavy, high-sided sauce pan
• measuring cups
• 13" x 9" x 2" pan
• butter (for greasing pan)

Directions: Butter the sides of the saucepan. Combine milk, sugar, and butter and stir until the sugar is dissolved and the mixture boils. Place candy thermometer into mixture and cook to soft ball stage (243° to 236° F). Remove from heat, then add mint wafers and marshmallows. Stir until blended. Pour immediately into a buttered 13" x 9" x 2" pan. Cut when cool and firm.

Procedure:

1. Prepare the fudge ahead of time according to the directions. Save an extra wafer and marshmallow to show students.
2. Ask students how igneous rocks form. (They are the result of magma, or molten rock, which has cooled.)
3. Show students the ingredients for the igneous rock fudge (marshmallow, wafers, etc.). Ask them to write their observations about these "rocks" in their science journals.
4. Pass out pieces of igneous rock fudge. Ask students to record their observations about these "rocks" in their science journals. You may wish for them to answer the questions below.

Questions:

1. How are the first "rocks" you were shown like the second?
2. How are they different?
3. What made the rocks change?
4. How do igneous rocks form?

Sedimentary Rocks
1 1/4 cups crushed flake cereal
1 1/2 tablespoons sugar
1/2 cup margarine


Melt the margarine. Mix with the cereal and the sugar. Press into an 8 x 8 or 9 x 9 pan.

1 cup chocolate or butterscotch chips
1 1/4 cups coconut
1 cup chopped nuts
1 can sweetened condensed milk (14 oz.)

Sprinkle the chips over cereal layer. Sprinkle the coconut over chips. Sprinkle the nuts over coconut. Pour condensed milk over the layers. Bake for 25 minutes at 325 degrees.

Sedimentary rocks are made in layers. The layers of mud, sand, or even seashells are built up over a long period of time. The layes get squeezed and stuck together to make new rocks. This cookie is made in layers and you can still see the layers even after it is pressed and cooked. NOTE! THIS ACTIVITY MUST BE DONE UNDER ADULT SUPERVISION!

You will need to gather these ingredients:

1/2 cup butter
1 and 1/2 cups vanilla wafer crumbs
1 (14 oz.) can sweetened condensed milk
1 (6 oz.) package chocolate chips
1 (6 oz.) package peanut butter chips
1 cup chopped nuts

Materials:

clear 13" by 9" baking pan
can opener
heat source
oven mitts

Steps to follow:

1. Melt the butter in the baking pan.
2. Sprinkle crumbs over the butter.
3. Pour condensed mild evenly over the crumbs.
4. Layer the remaining ingredients evenly over the top.
5. Press down gently. Bake at 350 degrees F for 25-30 minutes.
6. Let cool. Cut into bars. Enjoy!

    Metamorphic                Rocks

Conglomerate Cookies Become Metamorphic Munchies

by Deborah Hanuscin

Concept: Metamorphic rock formation

Metamorphic rocks are formed from sedimentary, igneous, or other metamorphic rocks. These rocks are subjected to intense heat and pressure. The heat and pressure are not quite enough to melt the rock, but they do cause the minerals in the rock to change in size or shape, or to combine with other minerals to form new or bigger minerals.

Objective:

Students will be able to explain how metamorphic rocks form.

Materials:

• toothpicks
• paper plates
• cookie recipe:
  • 1 cup butter, softened
  • 1½ cup light brown sugar
  • ½ cup sugar
  • 2 eggs
  • 2 teaspoons vanilla
  • 2¼ cups flour
  • 1 teaspoon baking soda
  • ½ teaspoon baking powder
  • ½ teaspoon salt
  • 1 cup chocolate chips
  • 1 cup peanut butter chips
  • ¾ cup butterscotch chips
  • ½ cup nuts (your choice)
  • Directions: Preheat oven to 350° F. Cream butter and sugars. Beat in eggs and vanilla. Combine flour, baking soda, baking powder, and salt, and gradually add to creamed mixture. Stir in chips and nuts. Place in spoonfuls on greased baking sheets. Bake 10-12 minutes.

Procedure:

1. Have students mix the cookie dough according to the recipe. Explain that the ingredients represent various sediments (small bits of rock) that they are combining to form sedimentary rock. By mixing, they are compacting the sediments. This particular type of sedimentary rock would be considered a conglomerate. It is made up of large sediments like sand and pebbles (the chips and nuts). The sediments are so large that pressure alone cannot hold the rock together, but they are cemented with dissolved minerals (the dough).
2. Ask students what will happen when you add heat to this mixture. Tell students that when sedimentary rocks are exposed to intense heat and pressure, they become metamorphic rocks. The heat and pressure are not quite enough to melt the rock, but they do cause the minerals in the rock to change in size or shape. Some minerals may be flattened, while others combine with surrounding minerals to form new or bigger minerals. While you will not be adding pressure to the cookies, you are adding heat with the oven. Spoon the dough onto the cookie sheets and bake.
3. When the metamorphic "rocks" are done, place them on a plate and ask students to "mine" them with toothpicks.

Questions:

1. What changes do you notice in the "minerals" of the rock?
2. Have some minerals changed and not others?
3. How are metamorphic rocks form?     
   

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