High School Chemistry part 2: Myths about Teaching Chemistry

There are some myths about doing chemistry that are important to homeschoolers.  Let’s go over a few of these:

Myth #1.  “You cannot teach chemistry at home if you did not take it yourself.”  (Or its corollary: You cannot teach chemistry at home if you don’t have a degree in chemistry, etc.)  I have met many parents who believe that this is true.  Parents can learn chemistry by reading the text just as their students can.  As well, homeschooling high school is not ‘parent spoon feeding the student’, but is student-directed self-study.  Chemistry can be learned this way as can any other subject.  What is required is a good, understandable text, a good amount of curiosity, and a willingness to be consistent.

Myth #2.
  “It takes $2000.00 to set up an adequate chem lab at home.”  I have heard this one at homeschooling conventions and it is patently wrong.  Since centuries ago, chemistry has been done in homes and can be done there today.  There are many very good books available either currently in print or reproducible with permission, which will provide a good laboratory experience.  The equipment is not terribly expensive, a good kit ranges from $100.00 to $350.00.  Even the Smithsonian chemistry sets in toy stores can be used to give a lab experience to your student.  Note that most lab manuals have been written for schools with laboratories and large-scale budgets.  Most of the common ingredient manuals are really more for elementary students.  So, how can you deal with this?  Simple, don’t worry about the labs you don’t have the materials for.  You should do about 25 -30 experiments during one year of chemistry.  (36-40 is better, of course)  So, choose your experiments from several sources, if necessary.  There are at least several manuals available that were written for homeschoolers specifically.  Experiences in Chemistry is one that was specifically designed to use everyday household equipment.

Myth #3.
  “Chemistry is too hard to do at home and should be taught by experts in school.”  Many homeschooling parents use chemistry as the subject to cover with a tutor, videotapes, or special classes.  These are great alternative ways to do chemistry, but they are somewhat expensive, whereas doing lab in a class for homeschoolers can be fun as well as a learning experience.  If you are thinking about a tutor, look into hiring a retired person from your church.  A retired chemical engineer can teach things about chemistry that no ordinary teacher would know.  If you plan on using videos, remember that a video does not substitute for laboratory experience.  Lab experience means using the equipment yourself, not watching someone else use the equipment.

Myth #4“Kitchen chemistry is the way to go for high school credit for your non-science major or non-college bound student.”  The chemistry of foods is a very complicated subject.  It is difficult to teach the foundations of chemistry simply by using a recipe book.  It is good to remember that Foods and Feeding is usually a very difficult course of study in college.  The fact that we all eat food does not mean that the chemistry of food is easy.  On the other hand, there are some good, edible experiments out there that can provide a great supplement to your chemistry studies, as well as being fun to do.

Myth #5.
  “One text is like another.  I’ll just pick up a used book from the school.”  Each text has good points as well as weaknesses, but they usually can be trusted to include the principles of the topic as well as some good problems for your student to solve.  However, there are differences in the texts.  One text might be good for your student, while another might totally turn him off to chemistry.  Read some of the reviews and see if you can spot the differences between the texts.  Some texts rely upon the student to work all of the math problems; others want the student to use analytical skills to solve non-math oriented problems.   One text may have the semester lined out with assignments, etc., while another may leave all that up to the student. If your student is self motivated he can use the later, while a less organized person will want to use the former.  Choose your text based upon the goals, skills, and interests of your student. (Yours, too)

Part 1: High School Chemistry!

Part 3: Resources for Teaching Chemistry

Comments { 0 }

Everyday Science: Contrails

It’s fall, and that means leaves falling, pumpkin pie baking, calendars rapidly filling, and ….. contrails forming.  So what exactly is a contrail?

Contrails (short for condensation trail) are man-made “clouds” created by aircraft engines when the temperature and humidity conditions are just right.  Usually occurring at temperatures below -40°C, and at altitudes above 26,000 ft, contrails are formed when water vapor condenses and then freezes on the particulate matter in aircraft exhaust.  To form a contrail, the temperature must be low enough or the humidity must be high enough for water to condense on the exhaust particles.  Since the process of condensation is well understood, it is possible to predict when contrails will form based on prevalent temperature and humidity conditions.

Typically, with fall weather comes cool, moist air aloft and conditions at are perfect for contrail production.  Think about it: do you see very many contrails in the summer months when it is hot and dry?  Sometimes contrails dissipate rapidly with high winds or high turbulence aloft, and sometimes contrails linger for quite some time.  Contrails dissipate rapidly with low humidity, since the newly formed ice crystals evaporate quickly.  With high humidity, persistent contrails are visible, as ice crystals grow in size, absorbing water from the surrounding (humid) atmosphere.  You might see a contrail which has been stationary for some time right next to one which is dissipating rapidly.  These contrails are at different altitudes, with different conditions at each level.

Since different gas composition, exhaust gas temperatures, and water vapor content exist in different aircraft engines, not all aircraft engines will produce a contrail at the same altitude (with identical weather conditions) at the same time.  Contrail formation has nothing to do with the type of aircraft or its speed.

Another form of contrail is produced when a portion of an aircraft such as a wingtip or winglet causes air cavitation in humid conditions.  Have you ever seen these vapor trails, perhaps at an airshow, when aircraft flying low over the airfield pitch up rapidly in high humidity conditions?  And since we’re mentioning winglets (shown below), you might be interested to know why they’re on the wing.  The winglet serves to reduce aerodynamic drag so the aircraft burns less fuel in flight.  This fuel efficiency is created by breaking up the turbulent wingtip vortices (pronounced VOR-ti-sees) produced by the pressure differential between the bottom and top of the wing.  No vortices = less drag.

Southwest Winglets

Back to the contrails, though… have you ever seen patterns in the sky produced by contrails?  Perhaps all paralleling one another or converging on a point?

This is no coincidence.  The world is criss-crossed with jet routes flown by all aircraft above a certain altitude.  At the junctions of jet routes are navigational aids, which you may have seen while driving or flying yourself.  Here is one navigation aid (navaid) in Oregon, shown courtesy of Wikipedia:

The aircraft whose contrails you see are each navigating with navaids similar to the one shown above.  Therefore the aircraft fly over the navaids as they transit the jet routes.  Parallel tracks of contrails are aircraft flying along the same route.  If you are ever curious about a contrail track you observe, you can check http://flightaware.com.  A screen shot near Dallas, Texas shows multiple aircraft tracks transiting along an east-west jet route using navaids.

Contrail predictions have been used since WWII, when the ability to spot enemy aircraft “conning” could make the difference in advance notice of an airstrike or positioning for air combat.  Here’s a graphic from p. 55 of the March 1943 edition of Popular Science identifying two types of vapor trail formation:

How about an activity to predict contrail formation?  NASA has an activity page where you can access  an Appleman chart.  Using the chart, you can construct a temperature profile to forecast contrail activity in your area.  The activity (recommended for 5th grade and up) begins this way:

…”Military planners have been interested in condensation trail (contrail) forecasts since World War II. Contrails can make any aircraft easy to locate by enemy forces, and no amount of modern stealth technology can hide an aircraft if it leaves a persistent contrail in its wake. In 1953, a scientist named H. Appleman published a chart that can be used to determine when a jet airplane would or would not produce a contrail. For many years, the US Air Force Global Weather Center used a similar chart to make contrail forecasts.

The first published reports of contrail formation appeared shortly after World War I. At first, scientists were not sure how contrails formed. We now know that they are a type of mixing cloud, similar to the cloud that sometimes forms from your breath during a cold winter day. Appleman showed that when the air outside of the airplane is cold enough and moist enough, the mixture of the jet exhaust and the air would form a cloud.

An example of a contrail-forecasting chart is shown below. We will use the chart to make our own forecasts, and make observations to determine whether they are true or false.

Appleman Chart

… Using either the temperature information provided by the teacher or the temperatures obtained from an Internet location (see note below), complete the table on the “Student Data Sheet”, then plot the temperatures corresponding to each pressure level on the “Appleman Chart: Student Graph Worksheet”. Connect the points to create a temperature profile of the atmosphere.

Note: Temperature and humidity information can be obtained from weather balloon soundings launched twice a day from several locations around the country. Several locations on the Internet including http://weather.uwyo.edu/upperair/sounding.html provide detailed sounding information. Choose the location nearest your school.”

This activity would make a perfect accompaniment to a physical science class, a weather unit study, or just a fun diversion.  If you have a weather station in your home, it would pair up nicely as an associated activity.  For younger elementary students, the NASA site also has a word search and a downloadable “Clouds and Contrails” craft.  Have fun!

Resources:

Comments { 0 }

High School Chemistry part 1

As our children get older, we are being faced with teaching upper level science at home.  Do you have reservations about doing science at home?   This post can help you approach high school science with confidence.  Science is the subject most mentioned by parents in my seminars as the reason parents send children back to regular schools.  And yet, science may be one of the best subjects for homeschooling because of the flexibility possible at home.  Let’s discuss some of the many options available for learning high school level chemistry at home. 

Chemistry is a difficult course.  In regular schools, students either take a minimum level introductory course or no chemistry at all.  The homeschooled student is different, however, and many are taking difficult courses like calculus, physics, law, logic, and world philosophies.  Homeschoolers should not be afraid of chemistry, either.  Some of that fear can be removed by learning about chemistry, what is involved in learning it, how a homeschooler can do chemistry lab at home, and how to plan ahead for chemistry.

What is chemistry and what is studied in high school chemistry?  Chemistry is the study of the matter that makes up the universe and the changes in that matter.  In a high school course, the student should learn about the structure of matter, the periodic chart, chemical reactions, the chemistry of life, nuclear chemistry, and some basic lab techniques.  Who needs chemistry?  Every student should take some type of chemistry.  Those students who will go on to college should take a more rigorous course and those who may never go on to college should at least take a foundational course that emphasizes real-life application of chemical principles.  Both of these groups should have lab experiences although the labs may be somewhat different.  Whether your student studies chemistry for one semester or for four semesters, he should be able to apply what he has learned to life.

What are the fundamentals of a high school chemistry course?  For a list of traditional topics normally covered in high school chemistry, check this blog entry.  For students using a non-traditional method of learning chemistry such a list can be a valuable help to keeping on track.  Check off topics as they are studied so that the student does not have to repeat topics already learned.  An example of this: suppose the student has studied the structure of matter, atoms, molecules, and compounds in 8th grade.  He should not have to repeat topics if he already knows the information.  So, he checks off those topics and during the first quarter of the year, reads over the material already studied in a quick review.  He then spends the remainder of the semester studying electron configuration, the periodic chart, and bonding; fundamental concepts he has not yet learned.  By doing this, the student has more time to learn the new material and, at the same time, is getting ahead of the normal schedule allowing him time for the more complex topics at the end of the book.  When you study the theory of chemistry you should not leave out the practical aspects of the subject.
   
Many students never really make the connection that chemistry is something they will live with for the rest of their lives.  They do not connect events in the laboratory with events in the garage or the kitchen.  The application of chemical principles to real life is very important to every student because in understanding these principles the student understands many events in the “real world”.  To help make chemistry real for your student, use a good plan for laboratory.

A homeschooler can easily have a real chemistry laboratory at home. There are several lab manuals on the market that use materials which are available to the average homeschooler and which will do an excellent job of teaching chemistry.  Check out the resource list in part 3 of this blog post for suggestions.  The materials do not cost a large amount, either.  In fact, if you buy a good chemistry kit (with glassware rather than plastic) when your children are young, you will get many years of use out of the materials.  Kits may contain the chemicals necessary to do the experiments, or chemicals can be bought at the grocery store or hardware store.  Have your student keep a lab notebook that describes the experiments he or she has done.  The best plan for building a home lab is to:

  1. Buy your equipment early
  2. Buy a lab manual and read it for materials required
  3. Make your purchases, ideally purchasing or borrowing only what you need to complete the prescribed labs
  4. Ensure the student keeps a lab notebook as the labs are completed.

Now, you have a list of topics for chemistry and a plan for getting your lab set up.  The next step is putting it all together.  This means choosing a text, a lab manual, and perhaps a few references.  These choices must be made based upon the goals, reading level, and math level of your student.  Remember, you do not necessarily have to do the teaching.  The primary role of a parent at the high school level, anyway, is facilitation (that’s where you provide the money and the wheels for your children.)  Your student should be able to do the reading and problem solving solo, or nearly so.  You may be needed to help interpret the text, discuss the material, and be curious; or, on the other hand, you could have another friend do these things.  One homeschooling mom from Colorado told me that she thought that the beauty of homeschooling is that the children learn to learn on their own.  Even struggling with hard things helps them learn so much better.  So, be encouraged; you can do this!

Each student learns differently and so, will need a different kind of chemistry course.  Here are some suggestions for different students:

Planning for chemistry for the non-science major who will probably not ever consider college is not difficult.  The concepts he should know are the fundamentals, the basic principles of chemistry upon which our lives depend.  A good text might be Usborne’s Illustrated Dictionary of Chemistry.  These books explain things simply and concisely.  Use Chemistry Experiments by Mary Johnson for lab. 

Your non-science major future college student will need a bit more rigorous course.  The A Beka text, Chemistry: Precision and Design, is very good and the explanations are excellent.  Chemistry in the Community (ChemCom) by the American Chemical Society is a great text and the labs are within the text itself.  Choose a kit from The Science Project Store, Science Labs.com (for ChemCom), or use Experiences in Chemistry from Castle Heights Press. 

If you have a student who is in 7th grade and very interested in chemistry, go for it.  Take out the list of fundamentals; get an introductory text, like Bob Jones’ Physical Science or A Beka’s Science of the Physical Creation, and just do the chemistry part of it.  Do the first part of Experiences in Chemistry for the lab.  When the child is older, just dive right into a high school level book and complete the laboratory activities already begun.  If you choose Science of the Physical Creation, you can do many of the lab activities at home provided you have a good lab kit. 

Your older college bound science lover can complete any of the usual high school texts or he or she can go right into the General Chemistry text by Umland for a rigorous start on college level material.  Remember the information is not different, there is just more of it.  For lab do Experiences in Chemistry, or a Chemistry kit from ScienceLabs.com such as the Chem C2000.  After the text is complete have your student take the Advanced Placement test in May.   If your student has used the normal high school level texts have him or her take the SAT II: Chemistry in the spring.

What about the parents who simply want a worry-free experience for their students?  Go to the local junior college and have your child take the general chemistry course.  It will be two semesters and the labs will probably be integrated into the course.  Don’t be afraid of night courses.  My son took one and the instructor was a retired chemical engineer who taught a great deal about vat chemistry in industry.  My son loved it. 

Now you know something about what is taught in high school level chemistry, you know how to plan for a laboratory at home, you also know several options for putting together a good chemistry course.  Learning chemistry requires effort, but is an excellent way to learn about God’s universe and the way it is put together.

Part 2: Myths About Teaching Chemistry!

Part 3: Resources for Teaching Chemistry.

Comments { 0 }