Category: general science

The study of volcanoes is a popular science topic and can easily be investigated as a unit study at home.  In this article, we will observe some of the characteristics, vocabulary, locations, and causes of volcanoes.  A family should be able to use this article to start a great unit and to introduce many other interesting topics.  Let’s start by understanding just what a volcano is.

According to the United States Geological Survey (USGS), a volcano is a vent or opening in the surface of the Earth through which magma erupts and also the landform that is constructed by the erupted material.  Magma is liquid rock with dissolved gases in it including water vapor.  When magma reaches the surface of the Earth, it is called lava. The liquid rock is kept so by the pressure of the rock above and by the high temperatures of the Earth’s mantle below.

Formation:  The theory of plate tectonics seems to explain well the things we can observe about volcanoes.  According to this theory, the Earth’s crust consists of plates atop softer, heavier rock.  Because they float on the surface of moving convection currents, the plates are moving, too.  The continents we inhabit ride on these plates and so are also moving.  In looking at a map, we see that most of the active volcanoes of the world are situated about the Pacific Basin in a configuration known as the Ring of Fire.  One of the plates the Ring of Fire surrounds is called the Pacific Northwest Plate.

Plate Tectonic Activity:  Observe a thick layer of fat floating upon the surface of cooled chicken broth.  Break the solid fat into plates and gently stir simulating the motion of the Earth’s plates.  Notice that three things can happen: the plates meet and slide one under another, two plates slide past each other, or the plates move apart.  If we did this to the Earth, magma could ooze to the planet’s surface.

Let’s look at each way plates may interact.  In one case, the edges of the plates crumple and one plate begins to go under the other one.  This seems to be happening on the west coast of the North American continent.  When the Pacific Northwest Plate plunges under the North American Plate, Pacific Northwest Plate is forced down (subducted) into much hotter levels, melting and forming magma.  The magma rises to form volcanoes which have produced the Cascade Mountain Chain.  Some of the mountain-building in the area is from the crumpling effect, and some is volcanic.

When two plates slide past each other, earthquakes, displacement of the land, rivers with jogs, and other effects of a transform fault can occur.  An example of this is the San Andreas Fault of California.

When plates move away from each other, magma from below flows up into the trench forming new plate material.  A good example of this is the sea-floor spreading in the Mid-Atlantic Ridge where the fresh magma is forming undersea mountains.

Most of the Earth’s volcanoes occur around the plate boundaries.  However, there are some interesting volcanoes which are not associated with the edges, but which are within the plates.  The “Hot-Spot” hypothesis seems to explain the phenomena we see, and so the hypothesis is generally accepted.  A permanently located “hot spot” in the interior of the Earth melts some of the material below a moving plate.  This magma flows up through weak places and forms great shield volcanoes.  The Hawaiian Island chain has been formed as the Pacific Plate moves over a “hot spot”.  As the plate moves, magma comes up in new locations producing more volcanoes and, eventually, new islands in the chain.

Structure:  All volcanoes are not the same.  Each type of volcano and each type of magma results in special landforms which vulcanologists study, measuring them and observing eruptions. Volcanoes made out of ash and coarse solid fragments form cinder cones which have a slope of about 30°- 35°.  In 1943, a Mexican farmer spotted a hole in the dirt with smoke coming out, and by evening, a small volcano had formed.  Paricutin, a large cinder cone, is now 1345 feet high.  Shield volcanoes are flat domes with slopes of less than 10° and are made up of basaltic materials   Mauna Loa is the world’s largest active volcano and rises about 30,000 feet above the sea floor; Mons Olympus on Mars is twice as large.  A spatter cone is formed when gas-charged lava is spit out of the vent into an irregularly-shaped dome.  A plug dome is made from cooler, sluggish lava which just cools forming a plug over the vent.  Composite volcanoes may be freeflowing one day and explosive the next because of their mixed lava, gases, ashes, and fragmented material.  These materials result in large volcanoes like Mt. St. Helens, Mt. Shasta, and Mt. Fujiyama in Japan.  Crater Lake is a composite volcano.  Formerly, the volcano was very large, dormant, and glacier covered.  Then, it blew its top in a tremendous eruption.  After the eruption slowed, a new top collapsed making a caldera.  Still later, the three cinder cones within the caldera formed and slowly the caldera filled with water.  The top hollow of a volcano is called a caldera if it is larger than 1 mile in diameter.  A smaller hollow is called a crater.  All types of volcanoes are interesting to study.

Volcanic Treasure Houses:  Another aspect of volcanoes is what the lava carries.  New water is released during an eruption along with other gases, like sulfur compounds.  The volcanic ash released into the atmosphere can cause a reduction in the total amount of sunlight the Earth receives from the sun, but also can provide nutrients for the land.  Diamonds and other gem stones are often found in cooled lava.  Obsidian, favored by the ancient Native Americans for arrowheads and implements, comes from lava which has cooled quickly forming small crystals.  Lava which cools slowly forms larger crystals like those found in granite, another igneous rock and a wonderful building stone.  There are many different and unique kinds of granite.  Llanite, a granite with blue quartz, can only be found in Llano, TX.  Many heavy, industrial metals are igneous rocks, as are the precious metals we use for currency: gold, silver, and copper.  Volcanoes have given us many things of value.

Crystal Formation Activity:  You can study the effects of different temperatures on cooling rocks by crushing and heating moth balls (paradichlorobenzene, pa-ra-di-chlor-o-ben-zene).  Melt the crystals in three jars set in very hot water.  After the crystals melt, place one jar into ice, one jar into warm water, and the last jar on a hot pad.  The crystals formed as they cool will be different sizes just like the crystals in granites and obsidian.

The study of volcanoes is fascinating and complex.  Discover new ways in which God has provided for us on this Earth by using the materials in the resource section below.  Go see some volcanoes and hike their surfaces.  Go into the Ice Caves of Oregon to see lava tubes.  If you cannot go to them physically, visit them on the internet.  The U.S. Geological survey has many great resources all available to homeschoolers.  View the videos on Mt. St. Helens and read about the eruption at Pompeii.  This is an important study and can lead to many other geological investigations, hobbies, and even careers.  Enjoy!

This article originally published in The Homeschool Link magazine.

If you have been around homeschooling for some time, then you probably already know what a unit study is and how you would incorporate it into your home school.  But if you are new to homeschooling, or looking for a different approach to your curriculum, or maybe just looking for a break from your normal classroom routine, you should hear about unit studies and how they can help with your schooling.

What is a Unit Study?
A unit study is a topical study that encompasses a wide range of disciplines.  Unit study is sometimes called a thematic, integrated, or cross-curriculum approach to learning.  The idea is to take a topic and study it in depth, covering every element of the topic as it relates to science, mathematics, literature, history, geography, and other disciplines that may be more individually tailored to the unit being studied.

This style of learning has been around a long time- can we even quantify how long?  Did Adam and Eve ever teach their sons and daughters about the world around them?  Think about when you or your children have been very interested in a topic and have dived into it to learn everything possible about that topic.  That’s a unit study!  But lets see if we can spell it out in greater detail with an example.

An Example of Unit Study.
Your ten year old has gone on a fishing trip with Daddy and is suddenly fascinated with everything involving fishing!  “Ah,..”  you think, “I just read an article on this, this would be the perfect opportunity for a unit study!”  What can an in-depth study of fishing uncover and how is it educational?  Let’s look.

Science (biology, botany, life science, etymology, ecology)

• In what habitat does a fish live?  How do humans interact with and affect that habitat?  Sketch your local fishing hole in terms of an ecological habitat.
• What are the different types of fish?  What is the largest fish?  The smallest?  What types of fish do you have locally?  Identify them with a wildlife guide.
• What are the parts of a fish? For what purpose was each part designed?
• What do fish eat?   Where do they fit in the food chain? (What is a food chain?)
• Do fish eat different things seasonally?  Do different types of fish eat different things?  Why do fly fishermen like to fish during “the hatch”?
• How do fish reproduce?  Draw the life cycle of a fish.

History/Geography

• Historically, why have we humans fished at all?
• Which countries or regions would you expect to consume the most fish and why?
• Describe historical fishing methods (boat, spear, nets, hands, fishing rod) and when/ where they were used.

Literature/ English

• Read Moby Dick
• Read The Old Man and the Sea
• Read a book on the history of fly fishing, or an anthology of fishing stories.
• Write book reports on the books you have read.  Discuss them in class.
• Write your own short story about fishing.

Physical Education

• Go on a field trip.  Fish!  Did you have to hike to the fishing spot?  That was PE.
• How many calories does one consume while fishing?  Does it depend on the style of fishing you are doing?
• Learn and try some different types of fishing.  Pole fishing, wading, floating, fly fishing…

Socio-Political Studies

• What controversies are involved in fishing today?
• Explain the principles of catch-and-release.  Why and when is this practice employed?
• Get a fishing license; review and discuss the rules and regulations.

How to Incorporate Unit Studies Into Your Homeschool.
Ok, so you just read the above example and it looks like a lot of work to put together something like that.  It certainly can be a lot of work.  But there are many resources available to help you wade the waters of a unit study.  Think first about how you want to use unit studies within your home school.

One way to employ the unit study approach is by throwing out the textbooks and diving into unit studies completely to learn all your core curriculum requirements.  This approach works best when homeschooling highly energetic children who need lots of hands-on practical application to stay engaged and to learn most effectively.  One could argue that we all learn this way best!  Remember, though, past about the junior high school level, if your goal is college prep for your children, there should be more rigorous coursework involved that will not be attainable through unit studies alone.  If you are using unit studies exclusively, you will want to do some research into your topic areas and tailor it to your home school.  Choose among available commercial products wisely to ensure you are hitting all the important subject areas for your children, and not simply having a great time… fishing, for instance.

Another way you can use unit studies is as a supplement to your normal coursework.  This is a perfect way to engage and round out a student who has a definite interest in one area.  Use your own activities and topic areas or purchase a unit study guide that addresses the area of interest.  If your child is old enough, let them proceed at their own pace and dig deeper into areas where they want to focus.  Make sure you incorporate some field trips and plenty of hands-on activities.  Have fun with it- this flexibility is one reason you are homeschooling, right?  Encourage your student.  Remember, career aspirations start this way.

A third way to incorporate the unit study in your homeschool is to take a break from your normal routine.  Take a few days, a week, or a month off of your typical class schedule to study one topic.  Then, at the end of the study, resume your normal classwork refreshed and energized.  You can choose a topic of interest to your student(s) or one that anticipates an upcoming event such as a family vacation.  You might have done this before without realizing it.  Did you ever incorporate some “school” into a family vacation?  Every vacation I can think of (although a theme park vacation might be a stretch) has some educational opportunities built in.  Gettysburg, Washington D.C., the Rocky Mountains, the Louis and Clark Trail, scuba diving in Cancun!  Take the week prior to the vacation and study up!  Incorporate science, math, history, literature, etc.

Benefits of using unit studies
Why would you use a unit study to teach your children?  There are several benefits to employing this approach.

First, choosing a subject that is interesting to your students means that they stay engaged and eager to learn.  When a unit study captures your child’s interest, they will want to dive in to all aspects of the topic.  Your job becomes easy- they will absorb anything you can teach them.

Second, the unit study can be used for your entire homeschooling age range at the same time.  By choosing age-appropriate activities for each child, you will allow each one to study the topic of interest at their own level.  Once again, your task is made simpler with fewer subject areas to address for the duration of your unit study.

Third, the unit study is by nature practical application oriented.  For your hands-on learners, a thematic study lends itself perfectly to maximize learning opportunities.  By providing a mix of different applications in the different disciplines, the unit study helps to combat disinterest!

These are some of the benefits of the unit study in your homeschool.  Whether you use it as a year-long approach or just to take a break from your usual routine, the unit study is a helpful tool for you to employ.

A Final Word
Whether you use a purchased unit study or one you have designed, have a plan in mind.  Write it down.  Tailor it to each of your children, if you are involving your entire home school class.  If you are engaging in haphazard hands-on learning, you are still learning, but it is best to have a concrete knowledge of your objectives and whether or not you met them.  Have fun!