Acid Comparison

• samples of calcite, limestone, or any rock containing calcite
• clear plastic cups (6-8)
• acidic liquids: vinegar, Coke, or apple, lemon, lime, orange, or tomato juice

• Predict levels of acidity from greatest to least.
• Put a calcite (or a rock containing calcite) sample in each one of 6-8 cups.
• Pour a different acidic liquid into each cup. You may choose to put students into small groups and have each group be responsible for a different liquid.
• Have students observe the initial reaction the calcite has with the acidic liquid.
• Leave the calcite samples in the cups for 2-3 days. Have the students observe the calcite sample and the liquid.

Refer to the Calcite Quest activity in the Earth Materials kit.

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Bread Rocks

• Wax paper
• Scissors or knife
• Rolling pin
• 2-3 types of breads (ex: white, wheat, potato)

• This activity can be done with students in small groups or as a whole-class demonstration.
• Stack 3-4 pieces of bread on a sheet of wax paper. Push down after adding each piece. Alternate types of bread (ex: put a white piece between two dark pieces).
• Have students observe the different layers and then push down on the bread. This is now a model of a sedimentary rock.
• Using a rolling pin, have students roll over the bread pile.
• Using scissors or a knife, cut the bread pile in half. Show the students how the pressure has combined the bread (like a metamorphic rock).

Sedimentary rocks are formed by the settling and hardening of mineral grains. Examples of sedimentary rocks include: sandstone, bog iron, rust, and limestone.

Metamorphic rocks are formed any rocks that have undergone a change to create new minerals or rearrange existing ones. Examples of metamorphic rocks include: quartzite, slate, and gneiss.

Weathering Tube

• Cardboard tube
• Crushed limestone
• Clear glass tile or dish
• Water
• Eye dropper

• Cut the cardboard tube in half lengthwise.
• Place the crushed limestone along the inside of the cut tube. Slant the tube on a slight angle.
• Place the clear glass dish under the bottom end of the slanted tube.
• Drop water from the eye dropper into the top of the tube and let it run down over the limestone.
• Collect water on the glass dish. Have students observe the water on the glass dish and discuss what happened.
• Evaporate water and observe glass dish.

The water is washing away small fragments of rock. These small fragments could be created by freezing or thawing. If the rain was acidic, it would also dissolve the rock.

Making Limestone

• Calcium chloride pellets (such as IceMelt pellets)
• Sodium carbonate (such as Arm and Hammer Super Washing Soda)
• white vinegar
• Small cups, test tubes, or beakers
• Droppers

• Make calcium chloride solution by adding one half cup of calcium chloride pellets to one quart of water. You may cap and store this solution.
• Make sodium carbonate solution by adding one half cup of sodium carbonate to one quart of water. Allow as much to dissolve as possible.
• Use a dropper to transfer about a milliliter (20 drops) sodium carbonate solution to a small cup, test tube, or beaker.
• Use a second dropper to add about the same amount of calcium chloride. Observe what happens.
• Evaporate liquid and observe remaining solid.

Limestone is calcium carbonate. The first solution contains soluble calcium, and the second contains soluble carbonate. They combine to form and insoluble calcium carbonate. Limestone, calcite, chalk, and egg shell, are mostly calcium carbonate.

Engineering Igneous Rocks

• chocolate chips
• heating surface
• sauce pan
• wooden spoon
• wax paper

• Melt the bag of chocolate chips in the sauce pan.
• Place small spoonfuls on pieces of wax paper.
• The children should watch as the chocolate hardens.

Conglomerate Creations

• Play-Doh
• sand
• wax paper
• variety of small rocks

Tips: Find examples of other conglomerate rocks and magnifying lenses.

• Give each child a small ball of Play-Doh on a piece of wax paper.
• Roll a small amount of sand into the ball.
• Now add several small rocks, either by rolling the ball into the rocks or having the children push the rocks into place. The rocks should be located throughout the ball.
• Let the "rocks" stand overnight in order to harden.
• Examine the new "rocks" with a magnifying lens and compare to other conglomerate rocks.

Conglomerate rocks are created by the cementation of various sized rocks without melting the parts. Conglomerate rocks are a sub-category of sedimentary rocks.

Physical Weathering

• eggs
• clay
• cookie sheet
• water

• Hard boil the eggs.
• Cut the narrow top off of the eggs.
• Remove the yolks.
• Make balls of clay.
• Using the clay, stand up each of the eggs on a cookie sheet, hole side up.
• Fill the eggs with water.
• Place eggs in a freezer overnight.
• Examine the eggs the next day.

The eggs are used in this experiment as models of rocks. Rocks undergo many changes due to weathering. One type of weathering is physical weathering, such as ice wedging. Many rocks have small indentations or cracks in them. When it rains and then freezes, ice forms in indentations and may expand, causing the cracks to become larger and changing the surface of the rock.

Making a Rubber Egg

• raw egg
• white vinegar
• plastic bowl

• Put the egg in the bowl.
• Add vinegar until the egg is completely covered by the liquid.
• Observe the egg for a few minutes.
• Let the egg sit overnight.
• Observe the egg again.
• Touch it gently.

Egg shells are made from calcium carbonate. Vinegar is an acid. When the acid is added to the carbonate, it dissolves it. The bubbles you see are carbon dioxide escaping from the solution.

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