Fluids Unit Plan
by Kevin Boyer
completed in partial fulfillment of the requirements for
"Teaching High School Physics"
Physics 301
Autumn 1996
Illinois State University
Carl J. Wenning, Instructor
Author's note: Many teachers choose to eliminate this unit to cover material that is then covered by college courses (who also skip this unit). After reading this, consider carefully before cutting this highly interesting and useful topic.
I. UNIT OVERVIEW
A. This unit focuses on the nature and properties of fluids, both liquids and gasses. The material is organized into a conceptual approach, and intended for high school physics or advanced physics students. The primary textbook used in this unit was Physics: Applications and by, published by Glencoe. This unit could be taught with any other standard high school physics text, but some of the concepts included in this unit plan may not appear in a particular text.
This unit can be adjusted in length. The content is organized so that each section of the unit is nearly self-contained, although each section builds on the previous. The amount of content, number of demonstrations, and number of labs is also variable. This allows this unit to be inserted into a variety of year-long plans. If all content is included, the unit can be expected to run between three and four weeks for a fifty-five minute, five days a week class.
This unit does require that students have some familiarity with forces. This puts this unit after basic kinematics and dynamics sections. The unit could conceivably be put second in a physics course, in a unit on matter, right after a section on energy. The sections on buoyancy and Bernoulli's equation would then have to be separated and taught after dynamics in order for students to make connections. This unit also assumes a familiarity with algebra, a prerequisite for most physics, but not all physical science courses.
B. After completing this unit, the goal is that students will have a working knowledge of the fundamentals of fluids and their usage in a technological society. Students should be able to understand basic similarities and differences between fluids and solids. Beyond just knowledge, students should be able to apply the principles in understanding common devices such as plumbing, and other applications of fluids. The state goals for science promote science literacy among students so that they can make judgments on scientific issues in a democratic society. This unit will fill students understanding of the role fluid power shapes our technological society.
C. Rationale- As stated earlier, his unit fulfills a necessary part in completing an understanding of the physical world. With a large percent of the earth surface, even a large percentage of human body composition, being liquid, it is surprising that many courses overlook this subject.
1. The student needs to understand certain principles, such as why it is necessary to be careful driving during the rain, but not necessarily when the pavement is only dew covered. The student needs to be able to master skills beyond just being able to use a scientific approach in understanding the world. Consider the difference a knowledge of fluid mechanics would make in being able to maintain a car. The lubrication system, the tires, even the very concept of internal combustion are deeply rooted in principles of functionality of liquids and gases. Students need to approach physical principles with curiosity, a willingness to learn, and a the ability to incorporate new knowledge.
2. It is beneficial to society to have students who know and apply what can be learned from this unit. There are many technological innovations that have become so commonplace that it is expected to have some familiarity with them. Leaving knowledge of such subjects to a technical elite will hinder the usefulness of making technology based on these principles available to the general public.
3. The scientific profession needs to stop brushing aside such a useful area of physics. Fluid dynamics completes the picture of understanding the states of matter. The math is difficult only in the case of turbulent flow. Eliminating this unit to spend more time on "problem solving" undermines the attempt of the scientific community to increase the scientific literacy of the general public.
II. RELATIONSHIP OF UNIT TO COURSE CURRICULUM
A. YEAR LONG CURRICULUM
Unit Topic Concepts Time
I. Intro - Math and Measurement algebra review, significant figures 2 wk
accuracy, precision, error, finding
meaning beyond the math.
II. Energy and Conservation potential energy, "observable" 3 wk
energy conversion of energy,
conservation of energy, universality
of energy, efficiency
III. Motion
a. Kinematics displacement, velocity, acceleration 3 wk
b. Dynamics forces, Newton's laws of motion, 6 wk
gravitation, energy of motion
projectile motion, harmonic motion
friction, circular motion, momentum
work, simple machines
IV. Properties of Matter
a. Solids springs, stress, modern usage 1 wk
b. Fluids pressure, internal forces, buoyancy 3 wk
fluid motion, modern usage
V. Thermodynamics kinetic theory, heat transfer, 2 wk
state changes, engines
VI. Wave Motion wave mechanics, sound, harmonics 2 wk
VII. Nature of Light particle vs. wave, optics 3 wk
VIII. Electricity and Magnetism
a. Electricity electrostatics, basic circuits, Ohm's 5 wk
law, modern uses of electricity
b. Magnetism magnetism, electro magnetism 3 wk
generators and motors
IX. Modern Physics atomic physics, relativity, 3 wk
basic astrophysics
B. The underlying focus of these units are to foster in the students a sense that the material covered in class is found everywhere in the real world. The units focus on real world problems, even at the expense of mathematical and "problem solving" mastery. All of the included units bring about a more complete understanding of how an understanding of physics brings a greater understanding of everyday natural events. Not included in this overall course outline is various projects that will encourage student creativity and research. These include such projects as mouse-trap cars, catapults, bridge/tower building, research on historical figures, etc.
III. CONTENT OUTLINE
A. The nature of fluids
1. Brownian Motion
2. Pressure
B. Liquids at rest - Hydrostatics
1. Incompressibility
a. Pascal's Principle
b. transmission of energy
c. the hydraulic press2. Cohesion
a. surface tension
b. internal friction
c. viscosity3. Adhesion
4. Pressure
a. determination
b. pressure into work5. Buoyancy
a. Archimedes's principle
b. specific gravity
C. Gasses at rest
1. Combined gas law
2. Properties of the atmosphere
3. Buoyancy
4. Pumps
D. Fluid motion
1. turbulent vs. laminar
2. pressure
3. Bernoulli's principle
4. Pipe friction
E. Combined States
1. vapor/humidity
2. volatility
3. solutions
IV. MAJOR OBJECTIVES
A. By the end of this unit, students will be able to define in writing certain terms and concepts. Students will be able to explain the molecular nature of fluids and how these relate on a large scale to physical properties of fluids. Students will be able to describe and give examples of physical principles of fluids, such as theory and determination of pressure.
B. Students will be able in the lab to set up and describe equipment that demonstrates principles of fluid principles. Students will be able to determine buoyant force, set up simple machines such as a siphon that rely on physical principles, and write at least a one page report on how a machine or appliance generally found in a household applies the principles learned in class.
C. By the end of this students will be able to describe or write a paper discussing the usefulness of applications of fluids. Students will be able to understand not only the advantages, but also the disadvantages in using fluid power. The students will be able to make meaningful arguments for and against using these devices, not avoiding understanding, but not blindly accepting either.
V. ALTERNATIVE CONCEPTIONS
A. Students will have undoubtedly had personal experience with water and other fluids in the real world. Students will have thus begun to form notions on the nature of fluids before taking this unit. It is likely that students will have formed some personal theories that are based on a few experiences and are not based on proven theory. The Handbook of Research an Science Teaching and Learning discusses in depth the nature of these misconceptions.
B. The Handbook itself does not bring any specific misconceptions related to the area of fluids. However, in researching for the unit plan, one author brought up a misconception that is so prevalent that even several text foster this misconception. When a fluid escapes horizontally from holes in a container, the fluid at the bottom hole leaves at the greatest velocity. The increased pressure nearer to the bottom creates the increase in escaping velocity. However, if the bottom of the container rests on a flat surface which the fluid hits, the fluid at slightly half-way goes out at the greatest distance. Many books showed the distance traveled by the escaping fluid increasing all the way to the bottom of the container. The fluid at the bottom goes nearly horizontal for quite some distance in some of these illustrations. The author jokingly suggests that if this assumption were true, drilling a hole at the very bottom of the can would create an escape velocity sufficient to send the fluid into orbit. This misconception is not fostered so much by student experience so much as it is a product of overgeneralizing the effects of pressure and not connecting projectile motion to the motion of a fluid acting under the same forces.
Another misconception is that the addition of a fluid between two solid surface such as a tire and the road, immediately causes a decrease in the coefficient of friction. The reality is that for a measurable amount, adhesive forces cause an increase in the coefficient in friction. This misconception is fostered by personal experience of slipping wall walking on even barely wet floors. Any raising in friction, such as papers sticking to puddles is attributed more to a "glue-like" bonding effect rather than adhesion. The connection simply isn't made.
VI. CLASSROOM METHODS
A. Even in A guide to Introductory Physics Teaching by A. B. Arons, a book specifically referenced for teaching techniques, the topic of fluids was only lightly covered in the miscellaneous section. This seems to follow the strange reluctance for physicists to cover the topic of fluids.
B. Aron's single section on fluids discusses how students don't truly generalize the concept of pressure when fluids of different density are mixed, then allowed to separate. The example is two fluids such as oil and water are mixed together. In the initial state, students correctly identify that the pressure on the walls of the container increases with depth, and is constant across the bottom so long as it is flat. When the fluids separate, students are often at a loss in describing whether the pressure in the container has changed. Students who do even attempt to find a solution often draw a diagram and conclude that since the shape of the container hasn't changed, that pressure still increases with depth, stays constant at a set level, and overall hasn't changed. The connection between pressure and fluid density is left out. Drawing diagrams is the suggestion Aron's makes in overcoming this incomplete understanding. Students should understand that this reduction in pressure is the reason the liquids separate in the first place.
C. This unit plan includes three lesson ready to use for this unit. As this unit is already one that can be placed at teacher discretion, it is an opportune time to use alternative methods other than simple lecture/problems/lab format. The three lessons incorporate inquiry methods while discovering topics related to fluids. The first uses an inquiry approach to explore a probably known effect of adhesion. The second lesson continues an inquiry approach into the nature of surface tension. The final lesson uses a cooperative inquiry approach that lets the students discover the relation ship of fluid density and object volume in determining the buoyant force.
LESSON 1:
Concept Change: Lubrication and Adhesion
Objective
At the end of this lesson, students should be able to recognize examples of adhesion and lubrication after determining coefficient of friction of a sliding mass.
Concepts
Misconception - with the addition of a lubricating fluid such as water, the coefficient of friction will always decrease, and never increase.
Coefficient of Friction - In a non accelerating system, equal to the frictional force divided by the normal force. Dependent only on surface properties.
Cohesion - The molecule to molecule attraction in fluids.
Viscosity - The amount of internal friction of the fluid. Related to cohesion.
Lubrication - A lowering of the coefficient of friction due to a fluid substance between the moving objects. Affected by viscosity.
Adhesion - The attraction between molecules in a fluid and adjoining non-fluid molecules. Creates a very weak, but measurable bond.
Sample Equations
For the main example, the following equations are used.
The masses are the pulled mass, and the suspended mass, respectively.
Lesson Plan
Intro - Lead into a short discussion of the visible effects of lubrication. Suggest an increasing lubrication effect with the increase of fluid. Do not suggest adhesion effects.
Example 1 - Push a black across the table. Then spray the table top and slide a small block across the table. This is an example of lubrication. An easier way is to have students slide their hands on table, spray, then try again.
Discussion 1 - Ask for a hypothetical relation between depth of fluid and reduction in the coefficient of friction. (lubrication) Draw a hypothetical curve.
Example 2. - Begin sliding block demonstration, drying after each record. add masses until static friction is just overcome, then record masses. Be careful of drying affects, poor surface matching, and porosity of materials. May need to respray periodically.
Discussion 2 - Discuss effects of adhesion. Create new hypothetical curve.
Example 3 (optional) - Explore effects such as change in moving mass shape, change in surface texture, or fluid, or effects on starting vs. kinetic friction. Do as time allows.
Example 4 . Stick a wet towel to the wall or wet spoon to nose.
Closure and Assessment. Ask students for explanation of final hypothetical curve.
Materials
low friction track sliding mass(es)
pulley and string suspended hanger and masses
spray bottle
LESSON 2:
Inquiry Approach: Adhesion and Surface Tension
Objective:
By the end of this lesson, students will be able to relate how raising and lowering surface tension indicates changing adhesion properties of liquids.
Concepts:
Cohesion: The attractive force between water molecules
Adhesion: The attractive force between liquids and other substances
Surface Tension: Phenomena on the surface of liquids where the cohesive forces cause the surface to behave like a membrane.
Surface tension and adhesion are dependent on the liquid and temperature
Materials: The following materials are used for this lesson
Sample liquids : water, oil, shampoo, soap, others as necessary
Sample objects : find objects with low absorption and calculable surface area
ruler balance scale picnometer
string beaker
spray bottle paper towel
Lesson Plan
Intro:
Spray water on vertical surface, blackboard is best. Show adhesion. Spray until water begins to trickle off. Discuss adhesion. Pour a little bit of water on the table, and relate surface tension.
Safety note: Remind students to clean up. Slippery when wet!
Discussion:
Have students predict which liquids will have a higher amount of adhesion. Ask them to explain their hypotheses.
Main Section: Have students roughly measure adhesion
1. carefully mass a beaker
2. pour in liquid and measure combined mass
3. immerse an object for a few seconds
4. pull out object slowly and let drip for a few seconds
5. remass the beaker
calculate:
1. density of liquid with picnometer
2. lost mass and volume
3. surface area of object
4. mass/area and g/area lost
compare with different liquids and different objects
use salt water to show density shouldn't matter
Discussion:
Give values of surface tension for liquids. Discuss the relationship. Liquids with a higher surface tension will adhere more to the objects.
Closure:
Soap and detergents lower the surface tension in order to decrease the adhesion of dirt and other particles to the body, clothing, etc. Ducks have oil on their feathers in order to have the feathers stick together better and repel water. Engine oil keeps engine parts from grinding. Discuss other examples.
LESSON 3
Cooperative Learning: Buoyancy
Objective:
At the end of this lesson, students will be able to derive the relationship between fluid density, volume of displacement, and the resulting buoyant force.
Concepts
Buoyancy: The net upward force on an object immersed in a fluid. This is due to the change in pressure form the top of the object to the bottom. The only variables that effect this value are density of the liquid and the volume of the object.
Lesson Plan
Intro: Refresh students on which variables affect the buoyant force: density of the fluid, and the volume displaced. Overview the procedure for the lesson and warn the students of safety concerns for the lab.
Divide the class into groups that will either vary the density, or the volume displaced. The conclusions from the separate groups will be combined at the end. Enforce to the students that every student is expected to have their hands on the equipment for some part of the lab. The only way to truly learn is to do, not watch or scribe the data. Enforce this especially among young women in the class.
Procedure:
1) Prepare the fluid to be used, and put into a beaker or some measuring container. Students should be able to explain why the amount of fluid does not matter.
2) The items being immersed should be such that the dimensions are easily calculable, and the object will not significantly absorb an of the fluid. Suspend this item from a balance or some scale that can determine mass or weight.
3) With the item still attached to the scale, immerse the item into the fluid (do not touch the bottom) and measure the change in mass/weight. Do not forget to indicate in which items the buoyant force was great enough that the object floats.
4) Repeat these steps, changing the density of the fluid, or the volume of the item.
5) If the volume is being varied, measure the volume either using the liquid displacement method, or by measuring the dimensions. For densities, a picnometer is best for finding an exact volume that can be weighed.
Analysis
The data should be graphed in order to find the effect on buoyant force. Students should argue on their own why the relationship is linear, and the intercept is zero. Do not bring up this point first, or allow any student to accept this with being able to explain why. A graphing program on a computer, such as the graphing program available through Vernier for the Apple is helpful.
Discussion
Students should argue on their own how to combine the equations. Give minimal assistance. Students should find the volume and density need to be multiplied to produce the results. With the right units, they should find Force = g * density * volume.
Materials
beakers objects, with attached string or wire
balance scale picnometer
various liquids
(the ones used for this lesson were tap water, salt water, and ethyl alcohol)
Safety Note: Be sure students are aware of procedure. Caution them that items may become wet and harder to hold. Be sure students do NOT try to consume any of the liquids (esp. the alcohol)
VII. DEMONSTRATIONS
Demonstrations that enhance the content of this unit are listed in order they can be included in the content. They are divided into major and minor demonstrations according to the amount of information that can be
MAJOR DEMONSTRATIONS
1. concept - Brownian Motion-nature of molecular motion
2. procedure - sprinkle pepper on the surface of a liquid. A Petri dish works best. Either place this on an overhead, or better yet have one for each student. Observe the various movement of the grains. A stereo microscope enhances this demonstration.
3. reference - observed in lesson plan of Becky Meyers, Illinois State University's Biology Department.
1. concept - Pascal's principle - incompressibility of liquids
2. procedure - fill two balloons (find ones that are resistant to bursting) about half-way with water. Attach the ends of each balloon to a water filled tube. Place each balloon in a can that allows the balloon to be just over the top and the tube to run between the balloons. If one balloon is squeezed, the expansion of the other balloon can lift even some small books.
3. reference - this demonstration was not referenced from another book. This is a demonstration learned quite some time ago.
1. concept - Effects on Coefficient of friction. Adhesion and Lubrication
2. procedure - drag a block along the table, with either force meter (or rubber band). spray on thin layer of water. Demonstrates adhesion. Trying adding more water, or if the right precautions are used, try a thin layer of cooking oil.
3. reference - described by Tom Holbrook, Illinois State University High School.
D. Tear or Sphere?
1. concept - adhesion and cohesion
2. procedure - place several large drops of various liquids on the surface of a board. Slowly tilt the board and observe the changes in shape of the drops as they eventually slide or run down the board.
3. reference - although based on theory, this was not referenced for a source
E. Filling cups
1. concept - viscosity (internal friction)
2. procedure - have two foam cups, one with a hole in the bottom, and a thin, straight straw going from this hole to a hole almost, but not quite, at the top of the second cup. Pour hot water into the first cup and slowly keep it overflowing. Time how long it takes for the second cup to fill. Compare this to the time it takes cold water to fill the second cup. The cold water will take longer due to increased viscosity. The straw makes sure the flow is not turbulent. If only one cup was used, the time it would take to empty from a hole would not vary with temperature due to turbulent flow.
3. reference - String and Stick Tape Experiments, R. D. Edge
F. The Leaky Can
1. concept -pressure to motion
2. Punch holes in the sides of a metal can at various heights. Fill the can with water and compare the angle at which the liquid leaves the can. Note that this is the experiment many texts (including R. D. Edge!) draw incorrectly.
Try with different water levels, hole sizes, liquids, etc.
3. reference - Potpourri of Physics Teaching Ideas, D. A. Berry
1. concept - buoyancy
2. procedure - suspend an object from a force meter. Measure the weight. Immerse the object in water and notice the evidence of a buoyant force. Explore the buoyant force by changing object mass, abject volume, object orientation, object surface area, depth, liquid density, and any other that students suggest.
3. reference - although found in many references, the procedure described was used in a classroom demonstration by Carl Wenning, Physics Department, Illinois State University
1. concept - density of gases/buoyancy
2. Attach two small balloons to the end of a meter stick. One needs to be filled with helium, the other with ordinary air. Either by spinning or moving linearly, find a way to accelerate the balloons along the direction of the ruler. The helium balloon will go in the direction of the acceleration, the air filled one will go opposite the direction of acceleration.
3. reference - Potpourri of Physics Teaching Ideas - D. A. Berry
1. concept - Bernoulli principle (liquid) - straw blowing water between two blocks held by springs
2. Place two blocks in a container, attaching them together lightly by string and by rubber bands to opposite sides of the container. Be sure block are spaced a slight distance apart and the rubber bands are fairly loose. Using either siphons, pumps, blowing through straws, etc., create a flow between the blocks. Observe the blocks moving together and staying close as long as the flow continues, but return to their position when it stops. (Take care that the flow doesn't cause the water to cycle around the other side of the blocks.
3. reference - String and Sticky Tape Experiments - R. D. Edge
1. concept - Bernoulli principle (gas) -
2. place a dime one cm from the edge of a table. Take a foam cup, place it 2 cm behind the dime with the lip 2 cm from the table. With practice, a person blowing across the top of the dime can get the dime to jump into the cup. This uses Bernoulli's drop in pressure relation.
3. reference - String and Sticky Tape Experiments, R.D. Edge
MINOR DEMONSTRATIONS
Changing Containers
1. concept - liquid seeks its own level
2. procedure - find several differently shaped container and pour the same water around between them. The stranger the shape, the better.
3. reference - Physics, Principles and Applications, Harris and others
1. concept - adhesion
2. procedure - works well with any flat object and decently smooth surface. Lightly wet a surface of the object - i.e., lick the flat side of a 3 x 5 card, and place it on the flat surface - like your forehead. Try sticking a spoon to your nose (I can't do that one)
3. reference - a common occurrence, spoon idea from Tom Holbrook, Illinois State University High School
1. concept - surface tension / cohesion
2. procedure - punch three holes near each other in a horizontal line on a can (can be same can from The Leaky Can). Run a finger across the streams so they combine. The water from three holes combined still flows combined even after the finger is gone.
3. reference - String and Sticky Tape Experiments - R. D. Edge
1. concept - buoyancy (density)
2. procedure - place cans of diet and regular cola in cold water.
3. reference - A Potpourri of Physics Teaching Ideas - D. A. Berry
The Cartesian Diver
1. concept - combined gas law / buoyancy
2. procedure - fill a 2 or 1 liter bottle (clear) with water to the top. put in an object that is fill with air, but barely floats. Mustard and Catsup packets with varying sized air bubbles make good divers and provide for a very good demonstration. Insert the divers, make sure the bottle is filled to the top, and place the cap on top. The less trapped air, the better. Squeeze the bottle and watch the divers sink.
3. reference - fairly common, but particular specifications provided by Jim Williams, Materials Supervisor, Illinois State Physics Department
VIII. LABORATORY ACTIVITIES
These laboratory activities generally follow the demonstrations that have already been presented in the class, but allow the students the opportunity to explore the material hands-on and in-depth.
A. Adhesion/Lubrication
1. concept - forces act between liquids and solids. Even though no real bonding takes place, These forces are of relatively large magnitude.
2. procedure - students will have a solid planar surface with a pulley at the end similar to that used in the demonstration. They are to set up the experiment and proceed in the following way:
a) Place one of the sliding masses on the surface. attach the string to one end, and extend this string over the pulley. Be sure both the surface and sliding block are either non-porous, or have been allowed to absorb water to saturation.
b) Attach the hanger to the end of the string. Add mass on top of the sliding object if the mass of the hanger is enough to overcome the static friction.
c) Add masses to the hanger until the weight just overcomes the static friction of the block. Find and record this value within about three grams.
d). Using the spray bottles as a standard, spray one spray per unit area across the track. As the bottles may not be set to the same standard between groups, do not exchange bottles. Repeat steps a through c.
e) repeat these steps for 2, 4, 8, and 12 sprays per unit area.
f) graph and compare the results of sprays vs. coefficient of friction.
g) As time allows, use blocks of different initial coefficient of friction, different planar surfaces, or different liquids.
reference - this lab is based on labs done by Tom Holbrook, Illinois State University High School
B. Surface Tension and Cohesion-
1. concept - changing the cohesion of the liquid molecules will change the surface tension of the liquid.
2. procedure - this lab measures the mass of liquid retained by a disk after being removed from a liquid. This measures the relative cohesive force between the molecules. Have students set up and proceed as per the following.
a) Suspend a round flat disk from a balance scale. Measure the mass of the object and string.
b) Immerse the disk into a test liquid. Allow the disk to sit for a period of about ten seconds. Note that it is a good idea to use a disk and string that do not absorb much liquid.
c) Slowly remove the disk. Be sure it is not moved abruptly and is kept level. Allow it to drip if necessary.
d) Remass the disk with the liquid. Calculate the mass of the liquid.
e) Repeat steps a through d for different size disks and different liquids.
3. reference - although based on theory from other sources, the procedure for the lab was not taken from any source.
C. Buoyancy (student directed)
1. concept - an object immersed in liquid will experience a net upward force from the liquid.
2. procedure - the students may be divided into two categories in the consideration of time.
a) Suspend an object from a balance scale and find its mass.
b) Immerse the object in a liquid. Find the new "mass"
c) Calculate the buoyant force, density of the liquid, and surface area of the object.
d) Vary either the density of the liquid or the volume of the object and repeat steps a through c
3. Analysis - show that the relationships of one variable to force is linear, and that together they determine that Force = g * density * volume
IX. SAFETY CONSIDERATIONS
A. The responsibility for safety in presenting this unit is shared amongst the faculty, and amongst the students as well. The principle is responsible for providing adequate resources and facilities for the classroom. The principal sees to availability of material resources, and maintains an awareness of state and national standards.
The science department chairperson is responsible for supervision and safety checks. The chairperson informs the teacher and administration of problems uncovered during these checks. Overall, the chair is a liaison between the administration and the teachers to ensure teachers understand policies the administration is enforcing, and the needs of the teachers are brought to the administration.
The teacher is responsible for instruction and supervision of the students themselves. The teachers are the true implementors, and thus are probably should be the most concerned with safety. Teacher should know to some degree all of what others are responsible for. Teachers need to know standards, how to acquire equipment, and how to maintain safety.
The students can not be irresponsible in their learning process. Students are expected to follow instructions and submit to discipline when they endanger themselves and other students, even if no harm was done.
B. The potential dangers include slipping, broken glassware, electric shock near outlets, and consuming hazardous liquids. Each one of these hazards can be reduced. The overall way to reduce hazards is to be aware of them, and not create a situation where a safety hazard might occur, unless it is well covered. To reduce slipping on floor or wet surfaces, any spills must be immediately cleaned. Broken glassware must likewise be immediately cleaned. If any electrical outlets are near, the ideal is to have them covered or shut off, and the liquids kept as far away as possible. In the event some water or other liquid spill onto an outlet, the best recourse is to call a maintenance worker. If possible, shut off the power, and rather than cleaning up, remove all students from the area and stay away yourself. Keeping the students from drinking liquids can be well warned, but in the event someone does get the idea to try drinking something, the school nurse is the best equipped to handle the situation. It might even be a good idea to have the student sit and the nurse come to the room to slow down the movement of the liquid. Overall, forewarned is forearmed
C. Each one of the demonstrations are possible hazards. However, the hazards for each demonstration can be easily reduced with the proper care.
X. SPECIAL STUDENT NEEDS
A. Having students with disabilities should not discourage the addition of this unit. Special accommodations have to be made to ensure the unit is just as meaningful to the disabled students as to those without disabilities. Consider a student with blindness or near blindness. The accommodations necessary to give the disabled student an equal opportunity to learn may take extra time for the teacher, but are necessary in order to be not only fair to the disabled student, but to meet the requirements of the law.
B. Immediately, the blind or visually impaired student would have trouble taking notes on paper, would not benefit from a blackboard or overhead projector, and would have difficulty with written handouts, homework, and examinations. In this particular unit, many of the demonstrations are intended to be observed, and the labs require the ability to read instruments and make observations.
C. Ideally, a system for the student to take notes and be evaluated will be worked out between the teacher and student by first few weeks of classes. Yes, this may take extra time for the teacher, but is required by law. For this model student to receive an equal learning opportunity in this unit, the usefulness of the different demonstrations becomes apparent. The blind student should be not only encouraged, but expected to get a hands on experience. This gives a good opportunity for other students to assist. It is also important to note the extra supervision while the disabled student is handling the equipment as a precaution against accidents.
It should be noted that hands-on should not be used only to serve the visually impaired. All students can benefit from doing rather than just hearing or being tested on.
One other consideration is the possibility that a blind student may have a seeing eye dog. The dog must be provided with a comfortable spot near the student. In the lab, or while doing demonstrations, the dog must be kindly so that it does not interfere with equipment or the liquids. Care and patience are required, because the dog does not respond to lecture. If the dog becomes a distraction, the class should not proceed without the student, who may leave to calm the animal, unless the student gives permission.
Overall, the student should be given the respect any other student would receive. The student has a disability. The teacher shouldn't create a handicap for the student.
D. Gifted students also deserve special attention. This unit is based on inquiry learning, and this gives a great opportunity for the gifted students to help out students who learn at a slower pace. So long as the gifted students are aware of the responsibility, they can lead demonstrations, assist the other students, and even tutor. For those gifted but not outgoing, special projects for some extra credit can be given, but the greatest reward for the student is to then use what the student has researched in a lesson and acknowledge them appropriately.
XI. RESOURCES
A. In deciding a textbook, El-hi Textbooks & Serials in Print, 1994 Edition was first consulted as to usual availability of texts. The list was used to find specialty books dealing with fluids to supplement the standard texts. The texts available at Illinois State's Milner Library were the group chosen from. Only one specialty text was found to fit the unit. Pneumatics and Hydraulics, the second edition of Fluid Power by Harry L. Stewart was one of only a handful of texts dealing with fluids, and the only one available at Milner Library. This book is written for more commercial usage, but is useful in finding current applications, and is used throughout the unit in finding examples.
The primary text, Physics, Principles and Applications, is primarily intended for the collegiate level. The only high school level text that covered the material with the same depth was Modern Physics by Trinkellman, published by as Physics. The reading level was approximately the same however, so Physics was chosen for its greater depth of coverage.
B. In constructing this unit plan, many of the materials used for the demonstrations are materials already available in most high school science programs, especially materials usually used for chemistry. Many of the materials are low cost materials available through discount stores or department stores. The only equipment that needs to be specifically ordered to ensure quality are:
microscopes - Brownian Motion demonstration
track, pulley, and hanger system - adhesion lab
beakers - throughout the unit
balance scales - used throughout the unit
force meters
the following equipment can be ordered, but available substitutions can be made
tubing - used throughout the unit
Other equipment, although considerable together, can be purchased at low cost.
XII. STUDENT ASSESSMENT
A. The labs in this unit should be graded on process understanding more than just process repetition. In the write-ups, the emphasis should be on explanation over correct answers. In the buoyancy lab, a paper that explains the theory well but gets a value of 9.6 for g should receive a higher grade than one than one that repeats the procedure from the sheet, but gets a value of 9.8. The following criteria would help in ensuring that the students are learning the skills, not just the knowledge.
1) Can the student perform the experiment with little help?
2) Can the student explain what he/she is doing while working?
3) Can the student successfully reword the instructions so another student could do the lab from the student's instructions?
4) Can the student show the process so that another student could do the work?
These three (in order) indicate an increasing grasp of the skills. Rather than testing each student, or even adding this to the grading criteria, this evaluation should be done in process while the lab is proceeding. A good way to reinforce these criteria is to compliment students who are reaching this level, or find some way of rewarding them.
B. For this unit, an ideal alternative assessment is to have the students look into real world applications of fluid mechanics. The students should be allowed to work in small groups if they desire, but a rubric that ensures cooperative rather than just group work should be enforced. This research should include not just a simple collection of knowledge, but a short argument on the usefulness of the application and a prediction of how useful this application will remain with the introduction of more advanced knowledge. For instance, a student who reports on steam turbines would be encouraged to look at its application in reference to nuclear power. A student might discuss the possibility of ships switching from oil fired steam turbines to alternative methods that still incorporate fluid mechanics such as solar heated steam turbines. It is necessary for students to be forming opinions on physics in the real world, not just being able to get the A in a classroom.
XIII. CONGRUENCE WITH STATE AND NATIONAL GOALS
Teachers have to work into their overall plans the goals of local, state, and national groups. Standards for physics have become more directed with the publications of The Illinois State Goals for Learning, The National Science Education Standards, and Project 2061. This unit fits well into the aims presented in these publications
A. At the state level, state educators want students of physics to have knowledge of certain key concepts, applications, and dispositions.
1. Concepts and Vocabulary, and their Application. With
2. Social and Environmental Implications of Technology.
3. Principles behind Research
4. Available Technology
B. The National Science Education Standards also set
C.
XIV. REFERENCES
Arons, A. B. (1990). A Guide to Introductory Physics Teaching. New York, NY: John Wiley & Sons.
Berry, Donna A. (1986). A Potpourri of Physics Teaching Ideas. College Park, MD: American Association of Physics Teachers.
Bowker, R.R. (1994). El-hi Textbooks & Serials in Print.
Edge, R. D. (1987). String and Sticky Tape Experiments. College Park, MD: American Association of Physics Teachers.
Gabel, Dorothy L. The Handbook of Research on Science Teaching and Learning. New York, NY: MacMillan Publishing Company.
Harris, N. C., E. M. Hemmerling, A. J. Mallmann (1990). Physics Principles and Applications. New York, NY : McGraw-Hill Publishing Company
Stewart, Harry L. (1976). Pneumatics and Hydraulics. Indianapolis, IA: Theodore Audel & Co.