Have lunch like a ROCK star!

I don’t know about you, but my children pick up, collect, and try to hoard rocks everywhere we go.  They love rocks of all different shapes and sizes.  While they are probably too young to make any serious attempt at classifying rocks, they often want me to tell them why rocks are different from one another.  I designed this lesson to show my children that there are three different ways that rocks are “born” so that they can begin to have an understanding of why they look different too.

Parent Background -  There are three main types of rocks:

Igneous –  Igneous rocks are formed when magma(inside the earth’s crust) or lava (on the surface) cool and become rock.  It may form crystals or not and is usually roughtly the same composition through-out the rock.  Common Igneous rocks are basalt, pumice, and granite.
                Photos:  http://en.wikipedia.org/wiki/File:Igneous_rock_Santoroni_Greece.jpg
                                http://en.wikipedia.org/wiki/File:IndianGranite.jpg

Sedimentary-  Sedimentary rocks are formed by the gradual cementing together or either small rocks, soil, or organic matter over time.  Examples, are sandstone, limestone, coal, conglomerates, and  mudrocks.  Fossils and clues to the history of earth are typically found in sedimentary rocks since they have not been destroyed by the heat applied to the rock.

             Photos:  http://upload.wikimedia.org/wikipedia/commons/c/c2/Banded_Iron_Formation_Barberton.jpg
            http://upload.wikimedia.org/wikipedia/commons/6/66/SEUtahStrat.JPG

Metamorphic -   Any type of rock (igneous, sedimentary, or older metamorphic) that is subjected to high temperatures or pressures after forming .  Familiar metamorphic rocks are slate, marble, and quartzite.  Metamorphic rock can be quite smooth or very bumpy with lots of inclusions.

                                Photo:  http://en.wikipedia.org/wiki/File:Migma_ss_2006.jpg
                                             http://en.wikipedia.org/wiki/File:Quartzite_2_jpg.jpg

Sedimentary Sandwiches

Materials Needed: 

                2 pieces of bread (two different kinds/colors if you have them)
                Your child’s favorite sandwich fillings using as many different items as possible
                Condiments
                Examples: Peanut Butter and Jelly with raisins on wheat and white bread
                                  Ham with two kinds of cheese, lettuce, and tomato
                                  Or get really creative if you have adventurous kids.

The set-up:  First look at a sample or the following picture of a sedimentary rock with your child.  Ask them what the rock looks like and if they don’t volunteer layers or stripes, add that into your description of the rock.  A sedimentary rock is composed of many layers pushed together and cemented over time.  Today they are going to make a layered sandwich for lunch.

Procedure: 

1.  Present all the sandwich ingredients to the child and let them know that they are going to make their own lunch. 
2.  The ingredients can go in any order just as long as one piece is of bread is on the bottom and one is on the top. 
3.  Let your child construct their own sandwich, then add the condiment cement yourself. 
4.  If the sandwich has gotten tall you get the extra fun of letting your child “apply pressure” by squishing it down.
5.  Make sure to look at the layers before getting down to the business of eating. 

Making the Connection:  Ask questions like the following –Did your sandwich look at all like the rock we looked at?   Did you put all your layers on at once or did they go on one at a time (it’s the same with sedimentary rocks – each layer was put on one after the other)?  When you bite through the sandwich does it all look the same or are there layers on the inside too?  What about if you bend this part of the sandwich in half – are there still layers?

Igneous and Metamorphic Rock Candy Dessert

Both Igneous and Metamorphic Rock are formed in the presence of heat.  In Igneous rock the rocks and minerals are fully melted into either magma or lava – this gives them a rather uniform texture and composition.  Metamorphic Rocks form when sedimentary rocks are subjected to heat and pressure over time and can be composed of many types of rocks at once so they often have a variety of shapes and textures within the same rock.  In the following activity, you and your children will use chocolate to make rock models that they will certainly want to examine more closely.

Igneous Rock Chocolate

Materials:
Chocolate Chips
Light Colored Chips (white chocolate, peanut butter, or butterscotch)
Microwave Safe Bowl
Wax Paper
Some type of mold to cool the chocolate in (can be a bowl, a Tupperware, a mini-loaf pan)
Access to a Microwave

Procedure:

1.       Grease or line your Rock mold with wax paper.
2.       Explain to your children that the two types of chips are different types of minerals and the microwave is a volcano that is going to melt them into lava.  We are now going to make a desert that is like an igneous or lava rock.
3.       Let your children pour each kind of chip into a microwave safe bowl. 
4.       We put it in the microwave and heated until melted about 2 minutes though I got it out every 30 seconds for the kids to stir.
5.       When fully melted, I stirred it all together once so that it all looked uniform and we poured it into the wax paper lined mold.
6.       Put it into the refrigerator to cool.

Metamorphic Rock Chocolate

Materials:
Chocolate Chips
Light Colored Chips (white chocolate, peanut butter, or butterscotch)
Chocolate Halloween Candy (we used a 2 mini take-five bars and a bag of milk duds, m&ms could have been my first choice, but they mysteriously disappeared from the Halloween candy overnight)
Microwave Safe Bowl
Empty glass Jar or Heavy Bowl to sit inside microwave safe bowl (used as a weight)
Cooking Spray
Access to a Microwave

Procedure:

1.       Spray the microwave safe bowl and the bottom of your weight with cooking spray.
2.       If your children are familiar with the butterfly life cycle explain that when the butterfly turns from a caterpillar into a butterfly we call that metamorphosis.  We are going to make metamorphic rock candy from other rocks.  Heat and pressure from other rocks on top of them make rocks change into metamorphic rocks.
3.       Let your children layer each kind of candy and the chips into a microwave safe bowl. 
4.       Next I filled the weight with water and placed it on top of the candy inside the bowl.
5.       We put it in the microwave and heated until melted about 3 minutes though I got it out every 30 seconds to check and push down on the weight..
6.       When the chocolate chips were fully melted and everything else looked gooey I gave it one final squish and we put it into the refrigerator to cool.

Making the connection:

When the chocolates were nice and cool (about an hour) it’s time to unmold and eat them.   Before eating, I had my kids look at them and I posed a few questions.  What does the igneous rock look like?  Can you tell we made it out of two different things?  Does it look the same all over?  How about the metamorphic, what does it look like?  Do they look the same or does the metamorphic have lots of bumps and things inside?  Don’t forget the most important question:  Which one is yummier?             

I hope you enjoyed our yummy foray into rocks and the next time your child asks what kind of rock it is, you can help them to determine if they think it is the same all through (probably igneous), layered (probably sedimentary), or made of all kinds of things heated together (probably metamorphic).