exploration lesson

use a two liter glass bottle ( a 64 oz juice container works well ) with an opening a little smaller than that of an egg. Fill it completely with hot water and then empty it. Immediately rest a peeled hard boiled egg atop the neck of the bottle. Within a minute the egg will begin to move through the neck. In another minute or so the egg will be pushed into the bottle. students will explode with questions and "answers." Listen.
At this time the teacher's role is to collect information students have about this amazing phenomena.
Many think they know the concepts which explain the egg's movement. However, misconceptions or as some say, "mixed concepts" are numerous. Children and adults mentally construct an answer for puzzling questions by "mixing" various "science truisms" they think will explain the phenomena. Often they present a incorrect answer but it sure makes "sense to them." These ideas are sometimes humorous but remember that students are not fledgling comedy writers. They are trying their darndest to explain a fascinating observation with all of the weapons in their arsenal of knowledge. Piaget was interested in a child's "wrong answers" because they often revealed more information about the thinking process than "right answers." A right answer might be just a lucky guess.

Before worrying about getting the egg out of the bottle, let's examine potential lessons to be learned.

concept introduction

this is a wonderful activity to "assess prior knowledge" before starting a unit on air pressure. There are an overwhelming number of science concepts that can be introduced, but the developmental level of the students will determine the depth to which this activity should be extended. Here is a primer of ideas:

• all motion is caused by unbalanced forces: more force in one direction than the other.
• the egg is pushed into the bottle by unbalanced forces
• the air pressure on the top of the egg pushing down is greater than the air pressure inside the bottle pushing upward ( thus, the downward and upward forces are not balanced ).

• air is a mixture of gases; mainly nitrogen (78%) and oxygen (21%)
• as a mixture, there are no air atoms or molecules; simply oxygen molecules mixed with nitrogen molecules; like the particles of a salt and separate particles of pepper
• air particles is the correct way to speak of the components of this atmospheric mixture

• air particles are always moving
• heat causes the particles to move faster and farther apart
• heat does not make the air particles themselves enlarge.
• faster moving particles exert more pressure than the same number of particles at a lower temperature.
• cooling cause the particles to move slower and move closer together.

A major problem occurs when discussing heat, temperature, and particle motion involved with this egg in the bottle activity. Ironically it resembles another egg problem: the chicken-egg controversy.
Which came first, the chicken or the egg ? In this case, which comes first, heat or increased particle motion? Does heat causes the motion of particles to increase or is the increased motion cause the heat ?
H eat is a measure of the total motion possessed by atoms or molecules or particles. Temperature is a measure of the average motion of the particles. A cup of hot coffee has a small number of particles moving at a very high average speed. Thus, it has a high temperature. A giant iceberg has a lower temperature, but much more heat than the coffee. This is because there are a huge number of particles moving "a little bit" ( compared to the coffee particles ) so the total amount of particle movement in the iceberg greater. If the particles move faster, by definition, the substance is hotter. Particles increase their speed by being near warmer materials. Through conduction, convection and radiation, heat energy is transferred to the cooler body. When any substance transfers its energy to the air, the temperature of the material drops while the temperature of the air increases. After the jar is filled with hot water and drained, air entering the container is heated by the warm glass. This makes the air particles spread apart and take up more space. Putting the egg atop the hole seals the container ( first dip the egg in water to help form this seal ). As the air in the container cools to room temperature, the particles move closer together and exert less pressure. The higher pressure outside pushes the egg downward. Note that the force causing the motion is high pressure coming from the outside and that there is no such force as "suction" working from the inside. After two or three trips through the hole, the egg often resembles a devil egg mixture, so substituting a water balloon about the size of an egg will provide an object with a longer "life span."

concept application

All air moves because of unbalanced forces. These forces are more commonly referred to as pressure differences or pressure gradients. Those "wiggly lines" on the national weather map are isobars ( iso = same; bar = barometer ) -- connecting points of equal air or barometric pressure. The pressure between any two lines is different enough to cause the air to move. Pressure differences can be stretched along a massive frontal system across three states, or simply the cold air flowing onto the feet of whoever is raiding the refrigerator. Grocery store display cases for frozen foods are often vertical chests with doors on them. When opened, the heavy, cold air flows downward, replacing the warm air and forcing it upward. Note that the warm air does not rise. Warm air is PUSHED upward by heavier descending cold air. Meanwhile, in the same grocery store, ice cream is frequently displayed in horizontal chests with no cover over it. This is because the heavier, colder air essentially stays in place and doesn't need a door to keep it from "spilling" upward or circulating.

Constructivism is nothing new. It is the common sense idea that all humans "construct" their own knowledge and values from their interactions with the world.
It is a laborious process.
It is slow. It is idiosyncratic.
It is personal. It is lifelong.
Often, it doesn't make sense. For example, people have been exposed to huge amounts of negative data concerning AIDS; teen pregnancy; not using seatbelts; alcohol and drug abuse -- yet many individuals "construct" in their minds, an irrational acceptance of these behaviors. There can be no "logic" to their choices for these actions because such decisions are governed the limbic or hypothalamic portions of the brain -- the centers of emotion.

In the realm of "traditional logic" -- the brain's neocortex is involved, and it is here that the many variables involved in understanding why the egg enters the bottle are processed. Within the neo-cortex the laborious, slow, idiosyncratic, personal constructivism of science concepts takes place. Hopefully, it will not take a lifetime. Maybe just a week.

Authors are wonderful examples of constructivists.

They have to say everything "in their own words," so that it "makes sense to them."

Writing is a laborious, slow, idiosyncratic chore, and this author has never read any article or book that he has written.

That is because in re-reading there would be re-construction of "this sentence" and "that paragraph," etc. It is akin to film stars who never attend their own movies. After being away from the computer or the stage for a while, the author or actor has new ideas about how to "do it." They are never satisfied. Students who miss a class often tell the professor, "Oh, I got Julia's notes, so I didn't miss anything."

Wrong.

What the absentee received was Julia's interpretation or "construction" of what she believed transpired in the session. The absent student did miss a lot. She missed the opportunity to construct her own view of what happened.

With these thoughts in mind, teachers have to be patient as each of her 27 students wallows through the thought processes to understand a concept. National or State curriculum planners live in a world of Idealisism and do not understand the importance of the time needed so each student "learn the concept." Syllabi get thicker and thicker and the school calendar is actually shrinking in the light of new demands. It is unrealistic to believe a constructivist teaching philosophy can be practiced under the time-strained conditions that exist in our schools.

With constructivists, less is best.

Teaching fewer concepts with full understanding is better than racing through a thick textbook that results in misconcepts and mixed concepts which equally frustrates teachers and students.

This activity allows teachers to classify many ideas about student thinking patterns and the changes these schema undergo with concept development. These changes are called constructivism. After the teacher's initial demonstration showing the egg going into the bottle, and before any group discussion, have students write their ideas about the cause(s) of the egg movement. The chart below will help researchers catalog the responses. Add other categories as needed. How often do students cite such ideas as . . .

HEAT MAKES THE - - -

atoms moving faster or slower
molecules moving faster or slower
particles moving faster or slower
atoms getting squeezed together
molecules getting squeezed together
particles getting squeezed together
suction makes it go in
air pressure pushes it in
vacuum is present
hot and cold are at war with each other
the egg shrinks
the neck of the bottle opens wider

Many children and adults confuse the terms, atom, molecule and particle. That is why all three "possible explanations' are provided in the chart.

Once small groups discuss the phenomena and students have had time to explore on their own, ask them to record their newest ideas about the egg movement. Place a wastebasket of hot water where students can rinse and heat up their containers before putting the egg or small water balloon on the top. See how the physical and social experiences help the student modify their initially incorrect ideas.

Piaget calls this moving from ( mental ) disequilibrium to equilibrium, or autoregulation. It is also called constructivism.

When students have constructed an acceptable explanation this problem, challenge them by asking how they plan to get the egg out of the bottle.

A quick egg exit is guaranteed by inverting the bottle and running hot water over it ( this may have to occur in the cafeteria; perhaps the only place in the building with a hot water supply and a sink deep enough to accommodate the large bottle ). The reason for the motion of the egg is an unbalanced force. The hot water flowing over the jar increases the motion of the air particles ( pressure ) and the egg is forced out. Is this an "egg-spulsion ?" To thank the cafeteria staff for their help with this project, students might make some badges in their best computer 'handwriting' that say, for example:
Ms. Anderson -- Official 5th Grade Science Egg-ucator.
A little "P.R." with the staff can bring year long dividends and enhance student respect for all the many non-teaching staff members that make the building "hum" and enhance the curriculum.

After getting the egg out of the bottle ask the students to record their thoughts which lists and explains the reasons for its behavior. Below are charts with categories covering the most "popular reasons" - both true and false - students believe the egg pops out of the bottle.

These charts can be used as a form of assessment. In the weeks that follow this activity, periodically check to see if students retain what they have learned about the movement of the egg. Ask them to answer these statements and then explaining choice. Their answers will detail which ideas were assimilated, and which are still puzzling concepts for them. Don't ask them all 15 questions at once. Perhaps three today. Two more next week, etc.

Repeat some segements of the "test" and chart the results. Is their thinking consistent ? Through time do some students finally "get it" -- and correct their previously errant thoughts ? Ahh -- if they did, they have constructed a new thought process and in so doing realize that science lessons are a real "egg-ucational experience."