Physical
Science Second Semester Lesson Plans for 6-8th graders
Topics:
Electromagnetic forces, electrical circuits, resistance, currents,
switches, magnetism, structure of an atom, periodic chart of elements, nuclear
force, radioactivity, sound waves, Doppler, wavelengths, light, reflection,
refraction, lenses, the human eye, the sun, nuclear energy, variable stars,
galaxies!
Goals
of this class: We will
discuss the topics listed above, but I also want you to learn some basic facts
which will carry you into adulthood about each of these topics.
In addition, I want you to learn to work properly with partners while
following scientific procedure. The
experiments that we will perform may or may not be easy, but they will easily
fail if you do not listen first and perform second. I will be giving test
grades, project grades, but we will also give you a grade for your performance
during experiments.
Grading
Grid:
15% per each Module 12-15 test. (Total 60%)
10% for Project of creating an atom—due week four
10% Class participation
10% Experiment procedures followed
10% of grade given for worksheets and notebook.
100% with grades to be handed out on Week Ten
**The students need to bring their notebooks every
week plus a pencil and colored pencils.
**I need to bring supplies for experiments each week.
Outline for
Semester
--Divide the students into teams for Module 12.
January 14th—week one—Module 12 in Dr. Wile’s book--discuss Electromagnetic force
January 21st-week two—Module 12 in Dr. Wile’s book--discuss Electrical currents and magnets if we have time
--Reshuffle the students onto new teams for Module 13.
January 28th—week three—Module 13 in Dr. Wile’s book--Discuss structure of an atom
February 4—week four—Module 13 in Dr. Wile’s book—The periodic chart of elements
February 11—week five—Module 13 in Dr. Wile’s book—nuclear force and radioactivity, radioactive dating.
--Reshuffle the students into new teams for Module 14.
February 18—week six—Module 14 in Dr. Wile’s book—Waves and sound waves, speed of sound
February 25—week seven—Module 14 in Dr. Wile’s book—Sound wavelength, Doppler, frequency
--Reshuffle the students into new teams for Module 15.
March 4—week eight—Module 15 in Dr. Wile’s book—Light, wavelength and
frequency
March 18—week nine—Module 15 in Dr. Wile’s book—Reflection and Refraction, color, lenses and the human eye. Hand in their notebooks for 10% of grade.
--No teams for the final week
March 25—week ten—An introduction to astrophysics—the sun, nuclear energy, variable stars and galaxies. AND Physical science bee for prizes.
We will discuss the topics listed on the syllabus, but more importantly, I want you to learn some basic facts which will carry you into adulthood about each of these topics. In addition, I want you to learn to work properly with partners while following scientific procedure. The experiments that we will perform may or may not be easy, but they will easily fail if you do not listen first and perform second. I will be giving test grades, project grades, but we will also give you a grade for your performance during experiments.
Like charges repel one another.
Part two of the experiment 12.1 demonstrates the second principal of electrical charge:
Opposite charges attract one
another.
We can now review one of the items that Physical science students learned in the fall with Mrs. Edge-- Newton’s Universal Law of Gravitation. What was Newton’s third law when you discussed mass? Does anyone remember?
Just like there were three principles regarding gravitational force, there are three principles regarding the force that exists between electrical charges. Give them hand-outs and then read:
All electrical
charges attract or repel one another, depending on whether they have opposite
charges or similar charges.
The force between
charged objects is directly proportionally to the amount of electrical charge on
each object.
The force between
charged objects is inversely proportional to the square of the distance between
the two objects.
Mass is the only word different in Newton’s Universal Law of Mass!
Electromagnetic force is produced through the exchange of particles, these particles are actually small bits of light, called photons. (We will discuss the concept more when we talk about light and the principles of light’s behavior. Apparently we do not see all of the light in creation.)
How objects become electrically charged?
Atoms contain positively charged protons and negatively charged electrons and neutral neutrons. Atoms are electrically neutral because they have a negatively charged electron for every positively charged proton they have.
When an atom loses electrons, it has more positive charges than negative charges and thus has a net positive charge. This is called a positive ion. When an atom picks up more electrons, then it has a negative charge and is called a negative ion.
How do atoms gain or lose electrons? One way is through chemical reactions—complex…see Mrs. Miller in a few years for an explanation!
11:40 There are two other ways that atoms can gain or
lose electrons. The best way to talk
about this is by building an electroscope. Experiment
12.2.
11:50 summary
What happened? The foil and the paperclip, like all forms of matter, have both a negative and positive charge in them. The number of positive and negative charges are equal…thus they have no overall charge.
The balloon picked up stray electrons when you rubbed it in your hair. Thus it had more negative charges than positive ones, and an overall negative charge.
When you brought the balloon into close proximity with the paper clip, the negative charge of the balloon repelled the negatively-charged electrons of the paper clip and foil. Since they were repelled, they traveled away from the balloon, which caused the ends of the foil to be rich with electrons. At the same time, the positive charges in the foil were attracted to the negative charges in the balloon. Thus they left the foil and traveled down towards the balloon. This made the foils poor in positive charges.
If enough time, will a bubble be attracted to an electrically charged balloon? If yes, why? If no, then why? Perform.
Charging by Induction.
Charging by Conduction.
II. Week Two, January 21st. Part II of Module
12.
To get electrical charges moving, you need something that generates the electromagnetic force. One device that does this is a battery. I can’t begin to tell you how a battery works, but for our purposes, we will know that the battery contains chemicals, which want to lose electrons ( the negative side) while the other side contains chemicals that want to gain electrons. (That is the positive side)
Vocabulary:
Electrical current is the amount of charge that travels through an electrical circuit each second.
Draw the circuit on the board with the battery showing like
this.
Scientists use drawings to symbolize the movement of the electrons through the circuit. However, Benjamin Franklin has caused some confusion regarding the drawings and how the electrons really move. Batteries were invented long before anyone really understood them and the electricity that they produced. Benjamin Franklin theorized that the electricity moved from the positive side of the battery to the negative side. This idea was readily accepted around the world, so people began to draw the movement of the electrons from the positive side to the negative side. This is known as the conventional circuit. Even though we know it is wrong, that is still how people draw a conventional circuit today.
Now that we know how to get electrons flowing through an electrical circuit, let’s figure out something useful to do with the flow of current.
In science they tell us that these collisions of electrons resist the flow of electrons. (act out with students?) Each metal resists electron flow differently, so we say that each metal has its own resistance.
Resistance is the measure of how much a metal impedes the flow of electrons
Resistance can also be determined by the size of the metal used. What do you think? Will wider pieces of metal or thin pieces of metal have the most resistance? Sure the wider, so the atoms can spread out with the electrons—few collisions. More resistance means more heat!
Practical applications: A space heater. They work because the material used to make the heater has a certain amount of electrical resistance. Since there is resistance, the electrons that travel through the material experience collisions. These collisions make heat and light. The light causes the heater to glow; the heat energy warms the room, cooks the food or browns the bread. So we can get electrons to do something useful in an electrical circuit by using a metal’s resistance to covert the energy of the electrons speeding through the circuit into heat and light. The metal you use will determine the effect you will get. Certain metals tend to produce more light than heat. What do you think those are used for? Right—light bulbs…
Let’s do some experiments to
check and see if we are right. Can a battery push/pull electrons through a wire
enough to light a small light bulb?
11:20-11:35-- Kids: Experiment Chapter 2, pages 18-19 in Science and the Bible, volume 1, Plug into God’s Power—Each group has one battery, one bulb and six inches of electrical wire.
When they finish: Hand out worksheets to show the path that electrons take to light the bulb.
One of the most useful aspects of the force that exists between charged-particles is that you can use it to make electrical circuits. One way to get charged particles moving is to attach it to something with electromagnetic force, such as a battery. Hook both ends of a battery together by metal and the electrons will flow freely from the negative side of the battery to the positive side.
NOW- Kids: Experiment: We don’t always need a battery. Let’s make a light bulb light up by using a lemon, a paperclip, light bulb, wire and a brass thumb tack. You find the way to make it work!
Kids’ Experiment: Salt Water experiment from Van Cleave’s Electricity book (found at the Harrington Public Library in Plano.)
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11:35--How do you think that light switches work if
we now understand electrical flow. What
can stop an electrical flow? OR
waves?
Experiment Chapter 25, pages 86-89 from Science and the Bible, volume 2, a Shield—need foil and a radio
What else?------------------What about a button between the battery and the wire? A penny? A quarter?
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Batteries are rated by their voltage which means how much push they have. The larger the voltage, the harder the electrons are pushed though the metal.
11:45 Give test over Module 12 beginning
--If they finish early ask them if a balloon with extra electrons will attract a bubble of soap. Perform.
For me to do: This week: Go to library and check out Fun with Science, Chemistry J 940 Par as well as molecules book, Van Cleave
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II. January 28th—week three—Module 13 in Dr. Wile’s book—cover pages 317-323 --Reassign experiment groups
Library book: How did we find out about atoms?
By Isaac Asimov and Molecules
by Janice Van Cleave. Another good
book is Adventures with Atoms and Molecules by Robert C Mebane and Thomas
Rybolt---J540.78 MEB at Harrington Library in Plano.
Discuss structure of an atom.
I. Introduction. Did you all know that people
used to believe that they could make gold. They
thought that they could become wealthy if they could just find the right
combination or recipe for gold. Is
this possible? Do any of you know
why it isn’t possible?
II. Atoms are thought of:
As early as 450 BC, the idea of atoms was thought of.
A Greek scholar or philosopher named Leucippus (lyoo-SIP-us) didn’t
believe it made sense to think that anything could be broken down into smaller
pieces indefinitely. Tear a piece
of paper up right now. He knew
that somewhere you had to come to an end. He
never lived to see his point proven
in science. However, he did convince
a few others to believe this way. His student, Democritus (dee-MOK-rih-tus) also
thought this way and he even gave the smallest pieces their name.
He called them atomos, the Greek work for unbreakable.
He thought that the whole world was made up of different kinds of atoms
and that in between atoms there was nothing at all.
III. Atoms are named:
Democritus couldn’t say why he believed this but he did.
It just seemed to make sense to him.
Over centuries many different scholars declared themselves to be atomists
too. In 56 BC, a Roman scholar named
Lucretius (lyoo-KREE-shus) even wrote a long poem in Latin. The poem in English
is titled On the Nature of Things.
IV. Evidence of atoms:
So when was there evidence of atoms?
Robert Boyle wrote in 1661 that elements must be discovered by
experiment. Chemists must try to
break down everything to the simplest possible substances.
Then, once they had something that couldn’t be broken down any further,
that was an element. So after
Boyle’s book was published, chemists began to look for experiments.
By the end of the 1700’s, they had discovered about 30 different
elements. Still not every scientist
was an atomist in the 1700’s.
V. Short list of atoms is discovered:
They had discovered elements such as copper, silver, gold, iron, tin,
lead, mercury by late 1700’s
VI. Models
of atoms: Even today we do not
know exactly what an atom looks like. Mrs.
Miller was telling me that originally they thought that atoms had a consistency
of plum pudding, but now they know that isn’t right either.
Atoms are mostly comprised of empty space, plus protons, electrons and
neutrons. Today we are going to learn the Bohr model of an atom, but we know it
is wrong just like the plum pudding model was wrong.
But for simplicity’s sake, we will learn this model and in chemistry
you can learn the more complicated models. The
Bohr model gives us a reasonably accurate picture of an atom.
VII. Size of atoms: The Bohr model tells us that
each atom consists of electrons, protons and neutrons.
The protons and neutrons are tightly packed together in the nucleus.
The electrons circle or orbit around the nucleus.
If we could make this model huge, the electrons would be at the edge of a
large baseball stadium and the nucleus would be the size of a marble.
The nucleus would sit on the field in the center.
That is how much distance there is proportionally between the nucleus and
the electron.
The space in-between is empty space. No air, nothing.
The size of the electrons is so small compared to the
protons and neutrons that we cannot draw an atom, because we couldn’t see the
electrons if we drew it so we could see the protons and neutrons.
VIII. Consistency of atoms: Each type of atom has a
different number of protons, electrons and neutrons, but there are some simple
principles that the atoms follow.
There is always the same number of electrons as there are
protons, which means that each atom should cancel out to a zero charge and be
stable. The mass of the atom is
discussed as being the number of electrons plus the number of protons.
The electrical attraction between the protons and the electrons holds the
atom together. These atoms are built
to a billionth of one percent specification. Any difference would blow them
apart. Tell me that this happened as
a part of evolution and that an intelligent being didn’t design the atom!
IX.
Atomic number is the number of protons in an atom.
The number of protons in an atom is what determines exactly what type of
atom it is. Two protons make it a
helium atom. If an atom has two
protons, its atomic number is 2 and it is identified as a helium atom.
Six protons make a carbon atom. But
atoms must have the same number of electrons and protons, so knowing the atomic
number tells you how many electrons and protons the atom has.
What about neutrons? The
number of neutrons doesn’t affect the nature of the atom much.
Thus the number of protons will determine the vast majority of the
atom’s properties. But the fact
that the neutrons have little affect doesn’t mean that they have no affect!
If an atom has too few or too many neutrons, then it will be radioactive.
We will discuss this in two weeks.
X. Mass of an atom: is determined by the sum of protons and neutrons in the nucleus. Next week I will hopefully give you a periodic chart of all of the elements that have been discovered but for today, let’s just talk about what we do know about atoms.
XI. Isotopes: Isotopes are atoms that have different numbers of neutrons. For instance, when you buy a helium balloon, it is full of helium gas, which is made up of helium atoms. However, some of the atoms have 1 neutron, some have 2 neutrons, and others have three. So we call Helium with 2 neutrons helium 4, because it has 2 protons plus 2 neutrons. Helium 5 has how many neutrons? You are right, three.
Taken directly from pages 317-323 of Dr. Wile’s book.
Before we do anything else, get them in their groups and do the following items for the second experiment:
Experiment 4.1
The chemical composition of water
Now that is done, let’s start simple and make a model
of the lithium atom today with our groups. Lithium
has a mass of 7 because it has three protons and four green neutrons.
What is its atomic number then? You
are right, three, because it has three protons.
Experiment: Molecules:
Make a lithium atom using wire and clay
If we were to combine two or more types of atoms, we
would get a molecule. Think of H2O. It
has two hydrogen atoms and one oxygen. But if you are like me, you wondered how
scientists knew this.
--Assign them homework to create a model of the atom and bring it to class next week.
Experiment 4.1 from Dr. Wile’s book. We will use a
9v battery and water to break water into to two hydrogen atoms and one oxygen
atom.
Clean up! Remind them of homework due next week.
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February 4—week four—Module 13 in Dr. Wile’s
book—cover pages 323-330—-------
1) Open with each one sharing their model of an atom.
2) Have assistants record grades for atom projects onto grade spreadsheet.
3) Tell them that I failed to tell them that the Bohr model only allows two electrons in the first orbit, eight electrons in the second orbit, 18 in the third orbit, 32 in the fourth orbit and finally 50 in the last orbit.
4) Quickly review last week’s discussion. Tell what is the size of electrons versus protons and neutrons. Electrons are smallest; protons are much larger, but just slightly smaller than neutrons. I heard someone ask if they could make a water atom. Can they? What is wrong with that question?
5) Introduce the periodic chart of elements. Hand out the charts. Emphasize how expensive these were. Treat them gently and don’t lose them. They can serve you well into high school and even college.
6) Let’s work out some simple math problems. All atoms that make up the element nitrogen have 7 protons. If a particular nitrogen atom has 8neutrons, what is it’s name? How many electrons does it have? Right, 7 protons because all isotopes of nitrogen have 7 protons. And since atoms have the same number of electrons as protons, we know nitrogen will also have 7 electrons. With 7 protons and 8 neutrons in the nucleus, the mass number is 15 (7+8), so we call this atom nitrogen-15.
7) Which of the following atoms is an isotope of nitrogen-15? What is its name?
a. An atom with 5 protons, 5 electrons and 10 neutrons
b. An atom with 8 protons, 8 electrons, and 7 neutrons
c. An atom with 8 protons, 8 electrons and 8 neutrons
d. An atom with 7 protons, 7 electrons and 7 neutrons. Right D…called nitrogen 14.
8) The element sodium is made up of all atoms with 11 protons. How many protons, electrons and neutrons are in a sodium-23 atom?
8) By 12:20, give them a pretest regarding structure of an atom and the atomic labels.
a. What force keeps the electrons orbiting around the nucleus? Electromagnetic force
b. Order the three constituent parts of the atom in terms of their size from smallest to largest. Electron, proton, neutron
c. What is an atom mostly made of? Mostly empty space.
d. At atom has an atomic number of 34. How many protons and electrons does it have? What is its symbol? This atom has 34 electrons and 34 protons. It is called Se.
7) Make Super chains form chapter 2 of Molecules book by Van Cleave
11) Close with a reminder that they will have a test next week at the end of the period.
12) Use any spare time to review for test. Using math problems.
This was as far as we got in week four, February 4th.
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February 11—week five—Module 13 in Dr. Wile’s
book—pages 330-340—nuclear force and radioactivity, radioactive dating.
I thought I would draw solely from Bob Jones Science 6 book,
chapter 8 about Nuclear reactions. I
thought I would do the experiment in the chapter with chemicals and bunson
burner. However, we didn’t do any
of that, and
Rewrite of week five—I deleted the radioactivity study rather than having to skip polymers and the video. We ran out of time for the full experience of the polymers because we did Spacey. I would delete spacey next time. Watch the video and then do the polymer stuff. Plus:
Give any stragglers a chance to share their project of an atom
8)Review last week’s final experiment making molecules. Then talk about space that is between atoms in a molecule. Experiment Spacey from Van Cleave’s book Molecules
9) At 12:25 watch a 10-minute snip from the movie Bigger,
Better, Faster from the FBCN Church library.
Then,
9)
12:35 Delta kit experiments. There are two. Do both and have them
fill out lab papers that I copied for them from the Delta kit. I am not sure
that the Delta kit needs to be re-ordered but just to have the supplies refilled
since we have the lab papers that come with the kit now.
10) Let them take the test home with them.
_____________________________________________________________________________
February 18—week six—Module 14 in Dr. Wile’s
book—cover pages 345-358—Waves and sound waves, speed of sound
Open with activity 66 from Developing Critical
Thinking Through Science, Book Two
Bring rulers, rubber bands, aluminum baking pans, pebbles and strips of paper. We do this activity to understand that vibrations produce sound and when vibrations stop, sound stops.
Then activity 67 regarding Traveling Sound.
Need yardsticks, watches metal spoons water and deep wide mouth glass
container. We do this experiment to
show that sound travels better through a solid or a liquid than it does through
a gas, such as air.
Next move on to Dr. Wile’s discussion of waves.
We know that sound travels in waves. Draw waves on the board. Say that this is what ocean waves would look like if we could see them from the side. Wavelength is from crest to crest or trough to trough. The crest is the top. The trough is the bottom. The amplitude is the height of the wave.
Surfers like waves with high amplitudes. People wanting to leisurely swim would want waves with low amplitudes. Frequency is how many waves will hit you each second if you stand on the shoreline.
In fact we now know that frequency and wavelength can be related to each other through the speed of the wave.
Frequency (f)= velocity(v)/wavelength (Lambda lower-case Greek letter)
Measure of units is meters by second. I get one per second, or a Hertz, in honor of the German physicist Heinrich Rudolph Hertz who discovered radio waves.
Define: Transverse
waves which are like ocean waves. The Ocean waves move horizontally toward
the shore but in doing so, they move vertically as well, the water goes up and
down. Thus these waves oscillate (or
known as HEAVE) vertically and propagate (or known as MOVE) horizontally. Longitudinal
waves are waves whose propagation is parallel to its oscillation.
Like a slinky! Sound is a
longitudinal wave!
Let’s use our math equation. F=v/lambda to answer a question.
What is the frequency of a wave that travels at a speed of
3 meters per second and has a wavelength of 0.5 meters?
Remember v means speed or velocity. So
f=3 m/second divided by 0.5 meters= 6 per 1/second
Instead of 1/second, let’s call it 6 hertz.
What does this mean? It means that if you are on the shoreline, then six
crests will hit you every second!
Sound is a kind of wave.
You can’t see sound waves like you can see ocean waves, can you?
You can see ocean waves because you see the water heave (or oscillate) up
and down. In physics terms, we say
that water is the medium through which the waves in an ocean travel.
There were some scientists who believed that sound waves
would not move if there wasn’t a medium for them to travel through, i.e. if
there wasn’t air molecules! In
fact, 2500 years ago, Aristotle believed that light and sound traveled through
the air like waves in the sea and he said that neither light nor sound could
pass through a vacuum since there wasn’t any air to transmit them.
It was almost 2000 years before the first vacuum was invented and
Aristotle could be proven right or wrong. Finally
in the 1640’s Evagelista Toricelli succeeded in creating a vacuum.
Do you think that Aristotle had been right? Were sound and
light able to travel in a vacuum?
Aristotle was wrong about light. It did travel right
through the vacuum without any hindrance. However,
Aristotle was absolutely correct, sound couldn’t travel without air molecules
to carry the waves!
We also now know that different mediums carry sound at
different speeds. Look at the hand
out from our activity earlier. The
Indians didn’t understand why, but they knew that sound carried better through
the ground or through railways than through air.
We cannot see sound waves in the air but we can see their effects, can’t we. This next experiment will clearly show that sound is simply vibration.
Experiment 14.1 The Medium thru which sound waves
travel. Make
a drum by stretching a piece of plastic over a large round tin, such as a cake
tin. Then stretch a rubber band
around the tin to hold the plastic taut. Sprinkle
sugar or rice on top of the plastic drum. Hold
a baking tray close to your drum and tap it smartly with a wooden spoon.
You will see the rice dancing up and down on the drum skin.
Hopefully you have been able to see sound today and you understand how we measure the speed of sound.
Vocabulary:
Amplitude
Wavelength
Hertz
Crest
Trough
Transverse wave
Longitudinal wave
Equation: f= v/lambda
Move means to propagate
Oscillation means to move vertically
Experiments last week led us to three conclusions:
Sound must have atoms to travel in. In a vacuum, sound cannot travel
Sound moves more quickly in certain mediums than in other mediums—gas versus liquid versus solid—why? Atoms are more tightly packed and carry the wave better than if far apart.
Sound moves in a wave
Let’s quickly use this tubing and funnels to retest what we learned last week. Tubing to make a stethoscope. Can you hear someone’s heart via air from here to there? No, now use the handmade stethoscope. Yes. Tubing carries the sound waves better than the air molecules did.
Now, let’s try it with a long piece of tubing. Listen up. Can you hear a pin drop from there? No, then try the tubing. Around the corner now?
Now we are going to talk about
Tell the equation that we ended with last week. Sound travels at different speeds depending on the temperature. Equation is v=(331.5+ 0.6T) m/sec Higher the number for T than the faster the speed of sound, right?
Think of a thunderstorm. What do you see first? Right, then what do you hear. Have they ever told you to count one-one thousand, two-one thousand? Then said that for every number you got a mile? Well Dr. Wile in our textbook says that for every second it is 1/5th of a mile.
Example 14.3 on page 354.
Supersonic speed….sound travels at different speeds in different substances. At times, we have been able to create an object that could travel faster than the speed of sound. We call that supersonic speed.
Supersonic speed is any speed that is faster than the speed
of sound in the substance of interest. IN
aviation, they measure a jet’s speed in terms of the speed of sound. Mach 1 is
knows as when a jet travels at the speed of sound in air.
The Concorde’s top speed is Mach 2.2 or 2.2 times faster than the speed
of sound.
Does anyone know what happens when an object travels faster
than the speed of sound? Right a sonic boom.
Sonic boom is the result of an aircraft traveling at or above Mach 1.
(Picture on page 357)
Sonic booms can be destructive to human ears, and building etc. After all sound is a wave of air. Remember last week when we talked about loud music does hit your eardrum and does damage it. Same principle here. Sound can shake a building and shake your ear drums. Therefore they ask that jets that travel at mach 1 or more, travel in low populated areas. The Concorde won’t hit Mach one until it is over the Atlantic Ocean.
Experiment c5, Singing Glasses, pages 28-30 in Science
and the Bible, vol. 1
Different sounds from the bottles were different pitches. Pitch is the highness or lowness of a sound.
Terms high and low do not refer to volume but to musical scale.
Empty bottles produced sounds with a long wavelength and
vica versa.
Remember wavelength and frequency are inversely
proportional to each other.
Play the recorder. When
you cover one hole you are shortening or lengthening the wavelength and thus the
pitch.
Our ears cannot detect all frequencies of waves.
We generally can hear only 20 Hz and 20,000 Hz.
Middle C has a frequency of 264 Hz. Waves
with frequencies higher than 20,000 Hz are called ultrasonic waves.
Waves with frequencies below 20 Hz are called infrasonic waves.
Discuss the moving car or ambulance with siren going. The
siren has a different frequency depending on where you stand to the vehical.
Experiment 14.4 The Doppler Effect—horn/car/street
Go now to the guitar experiment.
Experiment 14.5 The Amplitude of a Sound Wave.
The
amplitude of a sound wave governs how loud the sound is.
Sound turned up on the tv merely turns up the amplitude, or makes the
waves taller. A vacuum cleaner
typically has an amplitude of 60 decibels. A
soft whisper has 20 decibels.
Give test over Module 14 from 11:45-12.
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March 4—week eight—Module 15 in Dr. Wile’s
book—cover pages 373-382—Light, wavelength and Frequency and
Reflection—Take up tests—New experiment groups.
Okay, we have learned about sound and sound waves and about
atoms and electromagnetic force. Today
I want us to learn about light, but you are going to be surprised to learn how
much you already know about light! Let’s
start with some experiments and then we will come together at the end of the
class, around 11:40 to see what you learned!
Light travels in waves but also in particles.
White light is really made up of many colors.
If we separate the wavelengths of light, we get different colors.
ROY G BIV. Red has the
longest wavelength and violet the shortest.
This applies to what we already have learned about
wavelengths. Some we can hear, some we can’t.
Some we can see, some we can’t. Today
we are only going to talk about light which we can see, thus called visible
spectrum of light.
We are talking about an important subject so please do not
waste time—do as much as you can! But
remember that God mentioned light as a fundamental part of creation and it is
one of the first things mentioned in the Bible.
So take your study seriously!
Mary’s group-- do this experiment first:
Experiment 15-1
Seeing different wavelengths of Light
Supplies:
Flat pan
Medium sized mirror
Flashlight
White sheet of paper and water
Fill the pan with water, enough water to cover a significant portion of the mirror
Immerse at least a portion of the mirror in the water and tilt it.
Now shine the flashlight on to the mirror. Catch the reflection of the flashlight light as it bounces off of the mirror and onto your white sheet of paper.
Play with the tilt of the mirror and the position of the white sheet of paper until the reflection lands on the white paper.
If you play with the reflection enough, you should eventually see a rainbow. It may take a little work.
Questions:
1) What did you see in the experiment?
When light travels through different substances, it tends to
_____________________. The amount
that the light __________________, depends, in part, on the wavelength of the
light. Certain wavelengths
____________farther than others.
Experiment 15.2
Supplies:
A flat mirror
A white sheet of paper
A pen
A protractor
A flashlight
A black sheet of construction paper
Tape
1) Take the black construction paper and cut it into a circle that fits the face of the flashlight
2) Make it so that if the paper were taped to the face of the flashlight, little or no light would escape.
3) Next, at the edge of the circle of paper, cut a small slot—about 1/8 of the circle high and about 1/32 of the circumference of the circle wide.
4) Now tape the circle to the face of the flashlight so that the only light that escapes is through the slot.
5) Lay the white piece of paper on a rectangular table so that its edge is even with the straight edge of the table. Tape the paper down so that it doesn’t move from this position.
6) Use the protractor to make a line which is perpendicular to the edge of the table and is centered on the paper.
7) Take the mirror and push it up against the edge of the table so that the line you drew is centered on the mirror and perpendicular to it.
8) Hold on the flashlight and turn off the lights.
9) Hold your flashlight so that the slot is on the bottom of the face, touching the paper. Play with the way you are holding the flashlight until the light coming from the slot causes a beam on the paper which hits the mirror at the same point that the line touches the mirror. You should then see the beam reflect off of the mirror back onto the paper.
10) Use your pen to carefully trace the path of the beam as it travels from the flashlight and reflects off of the mirror.
11) Turn on the lights. Use your protractor to measure the angle of the line representing the path of the incoming beam relative to the perpendicular line that you originally drew.
12) Measure the angle of the line representing the reflected beam relative to the same perpendicular line.
13) Do steps 8-12 twice more, changing the position of the flashlight so that the angle which the incoming beam makes with the perpendicular line is different each time. In each case, compare the angle made by the incoming beam to that of the outgoing beam. What do you see?
**FYI—The angle that the light ray from the flashlight
made with the perpendicular line is the angle of incidence.
The angle that the reflected light ray made with the perpendicular line
is called the angle of reflection.
Pouring light
Supplies:
Water,
Flashlight
Empty soda bottle
Scissors to cut a whole in the bottle
Bowl to catch the water
Make a hole in a clear, plastic bottle.
Holding your finger over the hole, fill the bottle with water
In a dark room, shine a torch from behind the hole and let the water pour out into a bowl
See how the water carries light with it.
Making Light Bend
Supplies
Flashlight
Cardboard with a slit cut in it
Flat bottle
1) Fill a bottle with water and a few drops of milk.
2) In a dark room, shine a thin beam of light through the cardboard with a slit in it and through the flat bottle.
3) The light is refracted by the water
4) When it passes from water to air on the other side, it bends back the other way.
5) Refraction also makes water look less deep than it is.
6) Light bends because it travels at different speeds through different things.
7)
It travels faster through air than through water, but faster
through water than through glass.
Reflecting Power
Supplies:
Small flat mirror
White cardboard
Matte black cardboard
1) Set the mirror at a V angle with the first piece of white cardboard (They should be about the same size)
2) Turn the flashlight on in a dark room. Shine the light onto the mirror. The light reflected onto the card is almost as bright as the flashlight beam.
3) Replace the mirror with a white card. The flashlight beam is reflected well, but not as brightly as with the mirror.
4)
Testing black: Now
continue the experiment with a piece of black cardboard.
You will see that it reflects almost no light. The color black absorbs
almost all the light that hits it.
Experiment 15.4
The Magical Quarter
Supplies:
A quarter
A bowl that is reasonably deep and not transparent
Water
A pitcher or very large glass to hold the water
1) Place a quarter in the bowl.
2) Sit in a chair and position yourself so that you can see the quarter in the bowl
3) Now slowly scoot your chair back until you can no longer see the quarter, despite the fact that you are looking into the bowl.
4) Once you are at the point where you can no longer see the quarter, do not move your chair. Slowly begin to fill the bowl with water from the pitcher. Continue to look at the bowl but do not move your head. Eventually you should see the quarter re-appear.
5)
Question: Why did
the quarter re-appear? If you
don’t know the answer to this question yet, then continue with the other
experiments and come back to this question after you finish the other
experiments!
Splitting Light
More than 300 years ago, Sir Isaac Newton proved that white
light is made from the colors of the rainbow.
Newton split white light into a rainbow using a wedge of glass called a
prism. We see rainbows in the sky
because water droplets in the air split the sunlight before it reaches us
Make a rainbow
1) Get an adult to cut a slit in a piece of black poster board. Shine a lamp through the slit to be sure you get a narrow beam of light.
2)
Angle a mirror in a bowl of water. Bend a large piece of white
poster board away from the bowl.
3)
Shine a light through the slit in the black poster board and
onto the mirror. Adjust both pieces
of poster board until you get the best rainbow.
4)
You should be able to see all seven colors of the rainbow.
5)
Lastly, take a compact disc and shine a flashlight at an angle
onto it. You will be able to see that this can split light into a rainbow as
well.
Class Summary:
Light bends
Light doesn’t travel through all substances, but it
does travel through some
When it travels through some substances it is refracted
and/or reflected
A rainbow is a ____________________________
Get some books about light from the library. There are
so many good books and experiments to help you understand light!
Use this as a fun way to spend your time next week when N-Tech is off for
spring break.
_________________________________________________________________________
March 18—week nine—Module 15 in Dr. Wile’s
book—Reflection and Refraction, color, lenses and the human eye
Welcome back from spring break. I hope you each had a
marvelous week. We continued with school, but it was great to have a break from
N-Tech and Awana and our other extra activities!
Open with prayer.
Let’s review for a minute.
1) How did sound travel? In waves
2) Did sound need a medium to travel in? Yes, it needed atoms to carry the sound waves.
3) Does light behave the same way? No
4) What is the difference? Light travels without a medium.
5) Originally Sir Isaac Newton thought that light traveled in particles, or little packets. A Dutch physicist named Christian Huygens, who lived at the same time as Newton, disagreed. He thought light was a wave.
6)
It took the brilliance of a scientist, a scientist famous for
discovering the electromagnetic relationship to show that both men were right.
Who was that scientist? Dr.
James Clerk Maxwell!
7) Draw the figure 15.1, page 374, on the board.
8) James Clerk Maxwell showed that light is made up of two perpendicular waves. The first is an oscillating electrical field; the second is an oscillating magnetic field. Both the magnetic field and the electrical field oscillate perpendicular to each other, as well as perpendicular to the direction that light travels.
9) This is pretty heady stuff for me, so we will stop there. But remember that light waves are typically referred to as electromagnetic waves, which explains why light doesn’t need a medium to travel, the way sound does. It gets even more complicated than that, and scientists have come up with the quantum-mechanical theory of light.
10) The good news here is that we can use the same equation that we used for sound.
F (frequency) = v (Speed or velocity) divided by lambda (wavelength)
11) How fast does light travel? In air, sound travels at 340 meters per second or about 760 miles per hour. Light travels a LOT faster than sound. Light travels at 300,000,000 meters per second in a vacuum—or at 670,000,000 miles per hour!
12) Does anyone remember? Did sound travel more quickly through densely packed atoms or less quickly? Right more quickly as the atoms were closer together to carry the sound wave.
13) What do you think about light? Does it travel more quickly in tightly packed atoms? Light decreases the closer the atoms and molecules of the substance are.
14) IMPORTANT NEW INFORMATION: Einstein developed the Special Theory of Relativity….One of his primary assumptions is that the speed of light in any substance represents the maximum speed that can ever be attained in that substance.
15) As a result scientists today believe that nothing can travel faster than the speed of light.
16) Talk about wavelength and frequency. Draw a picture from page 379.
17) Just like wavelength and frequency determined the pitch of the sounds we hear, wavelength also affects the colors we see! Or don’t see!
18) When we did the experiment of shining light off of a mirror, through water, we saw a rainbow. What are the colors of a rainbow? Does anyone remember? ROY G. BIV
19) Wavelength of light determines its color. Longer wavelengths produce red. Shorter wavelengths produce violet…but even off the spectrum of color that we can see, Gamma rays or x-rays are shorter wavelengths. Longer wavelengths, beyond red are infrared light, microwaves and radio or tv waves.
20) Let’s do a quick experiment to see if the rainbow always turns out the same. Use water, markers and coffee filters. Let’s keep moving.
21)
Two weeks ago, we learned that light will reflect.
That I when light or even sound waves bounce off of an obstacle.
Remember our experiment with the paper taped to the table, the light and
the mirror. We saw that the angle of
reflection always equals the angle of incidence, right.--
--Experiment 15.5 How the Eye detects color
a. Get two plain sheets of white paper (NO lines on them) and a bright red marker.
b. On one of the white sheets of paper make a thick red cross using the red marker. The cross should be about 6 inches long. Make the cross bar about ¾ of an inch thick. Color the entire cross so you have a large, solid bright red cross in the middle of the white paper.
c. Take the clean sheet of white paper and put it beneath the paper with the cross on it.
d. Stare at the cross for a full 60 seconds. You can blink if you need to, but do not take your eyes off of the cross.
e. After 60 seconds, quickly pull the red cross away so that you are staring at the white blank sheet of paper for about 30 seconds. (There is a 10% chance that you won’t see anything, so write that if nothing happened.)
f. Write down what happened in your lab notebook.
g.
What happened? Do
not continue reading unless you have performed the experiment.
Most people will see a blue-green cross on the paper and then it will
vanish. This optical illusion will
not work for everyone. But why does it work most of the time?
In order to see light, the retina of each eye is equipped with rods and
cones. The cone cells are sensitive to color; the rod cells aren’t.
The cone cells transmit electrical signals to the brain whenever they are
hit by certain frequencies of light. The brain receives this electrical
transmission and converts it into an image in your mind.
Some cone cells are sensitive to only low frequency visible light (Which
would be red light) while other cone cells are sensitive to medium-frequency
light (green light) while lastly other cone cells are sensitive to high
frequency lights, blue light. So the
cone cells only send a signal of they are sensitive to what is hitting them.
Thus if a mixture of blue and yellow hits your eyes, the medium and high
frequency cone cells transmit signals to your brain.
Well, when you stared at the red cross, your low frequency cone cells
started sending a signal to brain that you were seeing red.
However, the cone cells get tired pretty quickly, so the low frequency
cone cells got tired and stopped working. While
the medium and high frequency cone cells were doing nothing at all.
When the brain stopped receiving signals, it assumed you were still
looking at the cross, and continued to hold the image in your mind.
When you yanked the red cross sheet away, your eyes were hit by white
light. White light contains all
frequencies, so all cone cells would need to be working to send signals to your
brain. However, your low frequency brain cells didn’t start back to work right
away, only the medium frequency and high frequency cone cells went to work at
once. Their message wasn’t complete without the low frequency message, so a
bluish-green cross appeared to your mind.
Your brain has only three types of cone cells. These cone
cells are sensitive to red, green and blue. From these three cone cells, your
brain can produce up to 16.7 million different colors.
The TV works the same way. From three primary colors, red, green, and
blue, it produces all of the color you see on your television set.
Why doesn’t paint act the same way?
Because paint is reflecting light, it isn’t generating light as a TV
can do. A TV or computer monitor
shines light into your eyes whereas dyes and paints reflect light into your
eyes.
Red paint is red for example because when light strikes red
paint, the chemical in the paint absorbs all of the wavelengths except red.
White light hits paint, but the only light we see reflected off of the paint is
red light. Green paint absorbs all
wavelengths except those associated with green.
What happens when you mix red paint and green paint?
Well the red paint absorbs all colors of light except red and the green
paint absorbs all colors except green. Between the two paints, all visible
wavelengths are absorbed and as a result virtually no light gets reflected and
we see black.
--Van Cleave from Family Fun January 2002 magazine, page 85—Show ink’s true colors
Hand out a quarter,
cups, markers and water for each student to perform.
See what colors are mixed to make blue?
Or to make black?
--Blue Skies and Red Sunsets, pages 26-28, Science and
the Bible, vol. 2
Give test over Module 15 for them to take at home.
We have been discussing light for the last two weeks of
N-Tech. Let’s now talk about the
source of light, or the main source of our light—the sun.
Everyone of you knows that our sun is a star, and not even a large star
as compared with other stars in the universe.
But let’s spend a little time talking about it anyway, so we can
understand how stars in general work.
Each star can be divided into four distinctive regions—the core, the radiative zone, convection zone and the photosphere. The core is the most active and the most interesting, so let’s just stick to that in our discussion today.
--the sun isn’t solid like the earth is. It is totally made up of gases
--90% of the sun is made up of hydrogen gas
--most of the rest is helium but there are other trace gases present
--hydrogen on our charts is the lightest, most simple element.
--despite the fact that hydrogen is light in weight, a lot of hydrogen together is heavy, very heavy—in fact the sun’s mass is roughly 2 million, trillion, trillion tons!
--this mass produces a very powerful gravitational field which holds the hydrogen in the sun, but also holds the planets around the sun
--because of this gravitational pressure, the core experiences massive pressure.
--because of this pressure, the hydrogen atoms in the core of the sun cannot exist in their normal form.
--Remember hydrogen atoms are very simple—one proton and either 0,1,2 neutrons, and one electrons—Different isotopes of hydrogen have different numbers of neutrons
--Well the enormous pressure in the core of the sun causes so much heat that the electrons in the hydrogen atoms escape and leave only a naked hydrogen nuclei
--these naked hydrogen atoms are constantly colliding with each other. They happen often and with much violence.
--When two H (2) nuclei collide in just the right way, they can fuse together and the result is a (3) He nucleus an a free neutron.
--this nuclear fusion results in the release of an enormous amount of energy.
--If you carefully measure the mass of two (2) Hydrogen nuclei, you will find that together they have more mass than the (3)He nucleus the and neutron that results after the nuclear fusion.
--What does that mean? It means that the mass of the two H nuclei is greater than the resulting He mass and neutron…so matter is lost in the fusion process.
--Where did the matter go?
--Remember Einstein’s Special Theory of Relativity that we talked about last week? This theory that assumes that nothing can travel faster than the speed of light.
--One of the consequences of this assumption is that matter is really just another form of energy.
--Very complicated ground here…we have to stay simple so I can understand it.
--Many scientists don’t even understand it, but they accept it and they have even developed an equation to relate mass with energy.
--A very famous equation…E = mc2 E=energy; M=mass; c=speed of light. But because the speed of light is so large a number, even a small amount of mass lost equates into a very large amount of energy!
--so nuclear fusion is transformed into energy.
--for instance, for every ounce of mass lost, enough energy is produced to run a 100Watt light bulb for 750,000 years.
--What happens to this energy? It moves to the radiative zone in the sun…eventually becomes light and heat!
:???????If the sun is 90% hydrogen and the rest is mostly helium, as time goes on, will that composition change? If so, will the amount of hydrogen increase or decrease?
(Hydrogen decrease, helium increase)
--Last vocabulary word for the semester—if nuclear fusion fuses two items into one, what do you think that nuclear fission does It splits one large nucleus into two smaller nuclei.
11:30 am Final Physical Science Jeopardy with 50 question cards made up. Each student can earn two cards and then they get a prize.
Hand out complete notebook information and final grades.
Assign homework to complete our study of the universe now that co-op is over.
Physical
Science
Parents and Students:
Welcome to the second semester of Physical and Earth Science!
We will use some fun tools this spring to experiment with physical
science while learning about the world our great God has given us.
My goal for the semester is for the students to leave our class with a
love for science and with ten relevant
scientific facts
that they can always remember and take with them into future studies.
As I have started reading up on our topics, I have re-learned that it is
fun to learn about science. Fortunately,
there are many scientists who have worked hard to bring science and scientific
principles down to the level of students and novices, like me. I pray that I can
spread their enthusiasm.
The students will receive a science notebook (spiral bound)
on the first day of class. We will
use that notebook every week as we perform experiments and discuss.
We will use the notebook to record questions and notes.
The students will be tested over the material after each module—four
tests. Each student will receive a
grade at the end of the semester. My
grading grid is below for your reference. Homework
is minimal and listed on the syllabus. Make
sure that your student brings the notebook to class every week!
Our study will use Dr. Jay Wile’s textbook, Exploring
Creation through Physical Science.
I am referencing chapters and modules in the syllabus.
My son, Cameron, will be required to read the chapters before each class.
If you own the textbook, I would recommend that you have your student do the
same.
I have developed our lesson plans to support science being taught in the home. I
believe 6-8th grade students need more than 10 hours of science
instruction during a semester to qualify for their science “credit”.
I am working to do the dirty work for you, the experiments. In order for
your student to benefit fully from this class, I would recommend you have your
students follow our topic line by reading books from the library or by reading a
textbook, even by another author.
I will not mark grades down if the students do not study at home, but our
discussions will be much richer if they are looking at our topics more than each
Monday during co-op.
Did I mention? Students should bring their notebook to
class each week, along with their pencil and colored pencils.
The note books will be handed in on the ninth week to be graded.
Please do not hesitate to telephone me at 972-596-1847 if
you have any questions about our topics or our class. I want the kids to have
fun, but I also will expect them to leave the class with some knowledge for
future building. In Him, Your
teacher
Grading
Grid:
15% per each Module 12-15 test. (Total 60%)
10% for Project of creating an atom—due week four
10% Class participation
10% Experiment procedures followed
10% of grade given for worksheets and notebook.
100% with grades to be handed out on Week Ten
The Class
textbook, Exploring Creation with Physical Science, was
written by Dr.
Jay Wile, but is not necessary for the students to own the book.
--I will divide the students into teams for Module 12 science experiments.
January 14th—week one—Module 12 in Dr. Wile’s book—discuss Electromagnetic force
Homework due for week two: Bring two facts about James Clerk Maxwell to class.
January 21st-week two—Module 12 in Dr.
Wile’s book—discuss Electrical currents and magnets. Test over Module 12.
--Reshuffle the students onto new teams for Module 13.
January 28th—week three—Module 13 in Dr. Wile’s book—Discuss structure of an atom
Homework due for week four: Bring a model of an atom to class next week.
February 4—week four—Module 13 in Dr. Wile’s book—The periodic chart of elements
Homework due for week five: Bring your element problems to class next week to be graded.
February 11—week five—Module 13 in Dr. Wile’s
book—nuclear force, radioactivity, radioactive dating. Test over module 13.
--Reshuffle the students into new teams for Module 14.
February 18—week six—Module 14 in Dr. Wile’s book—Waves and sound waves, speed of sound
February 25—week seven—Module 14 in Dr. Wile’s
book—Sound wavelength, Doppler, frequency Test over module 14
--Reshuffle the students into new teams for Module 15.
March 4—week eight—Module 15 in Dr. Wile’s book—Light, wavelength and
frequency
March 18—week nine—Module 15 in Dr. Wile’s
book—Reflection and Refraction, color, lenses and the human eye. Test over
module 15. Hand in their notebooks to be graded, 10% of grade.
--No teams for the final week
March 25—week ten—An introduction to astrophysics—the sun, nuclear energy, variable stars and galaxies with Physical Science Bee for prizes. Grades will be handed out this week when I return the student’s physical science notebooks to them.