sample discrepant events

8/7/2019 Sample Discrepant Events

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Sample Discrepant Events

Activities Related to Inertia:

1. Two Chairs (or Two Rollerblades/Iceskates): Action Reaction

You ask for two volunteers to do this activity. Depending on the availability and/orability of your students, you can use two chairs with wheels, rollerblades, or, if you

take students to an ice ring, two ice skates. The idea here is for students to see that

for every action, there is a reaction force.

Ask two volunteers two sit on the chairs, one is facing his or her back to other

student. Tell the students in the back seat to hold the chair in front of him/her andpush it. Everybody will witness both chairs moving away from each other, not just the

one being pushed. This means that the student who applied the pushing force (action)

on the chair in front of him/her was also affected by the same force (reaction) in the

opposite direction, and that is why he/she also moved away from the original point.

Here are some points to consider:

a. If you pick two students with equal weight, it is more likely that you will see bothchairs moving the same distance. This is because of the fact that action force is

equal to the reaction force in amount, and the forces are applied on the equal

weights. Thus, it is expected that both chairs move the same distance unlesssome other external factors are affecting, such as students sitting positions, floor

being carpeted, etc..

b. If you pick two students with two significantly different weights, then you can

also investigate Newtons 1st Law, Inertia, here. Do the activity in a similarfashion as described above. You can ask the heavier students to push first. When

the student with more weight pushes the chair in front of him/her, the student withless weight will move more than the student with more weight. Then, repeat thesame procedure by asking the student with less weight to push. When she/he

pushes the student with more weight, still the one with less weight will move

more. The reason is this: As we know from the first part that action force =reaction force, but in opposite direction. So we have two forces in equal

magnitude action on two different amount of weights. The force is big enough for

the smaller weight to move further. However, it is not big enough to move theheavier weight the same distance. To make it clear, lets use numerical values:

1st student weighs 50lb, and the second student weighs 70lb. The one pushes

applies 10Newton force. So, whoever pushes, they apply 10N force on each other.

10N applied on 50lb will not have the same affect when applied on 70lb. It willmove the less weight to further distance. It is because of the idea promoted by the

Inertia: It is easier to make lighter objects move because they have less inertia.

Even a little force will be enough to make them move. The heavier objects, on theother hand, will require greater force because they have more inertia.


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2. Pulling the Tablecloth: Inertia

To make this activity interesting and attracting, prepare the activity as a dinner table.Have a small size cloth, a plate or plates, utensils, glass cup and a paper cup, candles,

and anything else that you may find at a dinner table. When you collect these items,

make sure that they are made of different materials and have different weights. Forexample, you can have a paper plate, glass cup filled with water, paper cup with no

water, plastic knife, metal spoon and fork. The reason is to show students the

difference between the way heavy and light objects act when pulling the table cloth.Put some portion of the table cloth on the table, rest should hang down from your side

of the table. It is where you will hold and pull the table cloth. Set a dinner table for

one person. If you want you can have a heavy (glass or metal) candle holder with lit

candle. When everything is all set, ask students to observe what happens. And pullthe table cloth as quick as possible. You will see that heavy objects will not change or

slightly change their position while lighter objects, such as plastic knife or paper

plate/cup, will change their position great deal. It is because of the idea promoted by

the Inertia: It is easier to make lighter objects move because they have less inertia.Even a little force will be enough to make them move. The heavier objects, on the

other hand, will require greater force because they have more inertia.

Activities Related to Air Pressure:

1. Air is there:

This first activity is to prove that air is a matter, occupies space and it is not emptiness

meaning it has weight. Ask students to open their arms and move them around.

What do they feel? They feel breeze or some might say they feel the wind. You canmake a point that it is air what they feel. If they can fee it, is it really emptiness? You

can also blow balloon and ask them if they know what is inside the balloon. The

answer is air, of course. What made the balloon expand, or get bigger? Air. If theballoon is filled with air, does air occupies space? This is a harder subject for the

lower grades so keep it simple.

2. Air is there:

This activity shows that air occupies space. Take a glass, a paper and a glass (or

transparent) container filled with water . Make a paper ball by using the paper and put

it to the bottom of the glass. You need to make sure that paper stays at the bottomwhen you turn the glass upside down. When the glass is ready, turn it upside down

and put it in the water. You will see that water will go a little bit inside the glass but

not entirely. When you take it out (DONT BEND IT TO THE SIDES), you will seethat the paper is still dry. This shows that there was air inside the water which

prevented the water from coming in. Therefore, you can conclude that air occupies

space and it is a matter. It is not emptiness.

3. Air is there:

This activity shows that air pressure is very powerful. You fill a glass with water and

then use an index card to completely cover its mouth. When you turn it upside, youll


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see that water stays inside the water. It will look like as if the paper is able to hold the

water inside the glass. However, it is the air pressure that pushes the index card up,

which prevents the water from falling.

4. Love Thermometer: Boyles Law (Pressure - Temperature)

This happens because the air inside the bottle warms up by the heat transferred from

the hands. As the air warms (as its temperature increases), the molecules starts

moving around and hitting the inner surfaces of the bottle and the surface of the waterfaster. The warm air molecules are not strong enough to explode the bottle, but they

are strong enough to put pressure on the water. Because there is only one way the

water can move, it starts moving up inside the straw. This is also how thethermometers work. The difference is the liquid used in the thermometer, mercury.

Mercury is more sensitive to temperature difference so it is easier to make it move.

5. Crashing Can: Boyles Law (Pressure - Temperature)

In this activity shows how big and strong the air pressure applied on us. You need an

empty soda can, water, heater, big container. Fill the empty soda can with little water

(lets say of the bottle is filled with water). Then, put it on the heater until it boils.Fill the big contained with water as well. Once the water boils, hold the can with a pot

holder and bring it over the big container. When you feel ready, turn it upside down

as you put it into the water inside the big container (BE CAREFUL: YOU HAVE TODO THESE TOGETHER. DO NOT TURN THE BOTTLE UPSIDE DOWN FIRST

AND THAN PUT IN THE WATER BECAUSE THE WATER WILL FALL OUT

FROM THE CAN, WHICH WE DONT WANT TO HAPPEN). As soon as you putthe can inside the water, the can will crash inward. It is because the air pressure

applied on the can is greater than the pressure inside the bottle. So the great air

pressure crashes the can. Now because we are also in the same environment with the

crashed can, it means that same air pressure is actually applied on us as well.

Coloredwater

Glass straw

1-wholestopper

Glassbottle

Prepare the bottle as shown in the figure. Only point you need tobe careful is the stopper. Make sure that the stopper first into the

mouth of the glass tightly so that no air can go out or inside. Same

with the glass straw that goes through the stopper If you cannotfind a stopper, then you can use play dough. Wrap the play dough

around the straw and then place it in the bottle. Make sure you

tightly close the mouth of the bottle with the play dough. The onlyplace the air should be allowed moving in and out is the straw.

Once the bottle is ready, tell students that this bottle measures how

much love they have. Or you can come up with any other scenario

you want. Ask a volunteer to hold the bottle very tight with twohands. Make sure that the student holds bottle from the top part of

the bottle which is filled with air. It is because air transfer heat

faster than the water. As the student holds the bottle tight, youllsee the colored water moving up in the straw.


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6. Candle in the tube: Boyles Law (Pressure - Temperature)

This activity also works the same way as 4th and 5th activities. You need a candle (asmall birthday candle), small piece of play dough, colored water, a test tube,

matchbox and a clear container. By using the small piece of play dough, place the

candle in the center of the container. Then filled the container with colored wateruntil it covers the play dough, or a little bit above the play dough. Make sure that you

dont cover the candle with water. Light the candle and tell students to observe what

happens. Then slowly put the test tube over the candle until the open end of the testtube reaches the water. Your students see some bubbles when the test tube touches

the water. Then water moves up inside the test tube and candle goes off. It is because

as you cover the candle entirely with the test tube, the air inside the test tube starts

getting warmer and moving faster. As they move faster, they will start escaping fromthe test tube. This is why you see some bubbling action when the test tube touches the

water. Since some of the air molecules escaped from the test tube, there is less air

pressure inside the test tube now. And it is less than the outside air pressure. Because

of that outside air pressure pushes the water downward inside the container. Becausethe only place available is the tube, water moves up inside the test tube and

extinguishes the candle.

7. Lungs: Boyles Law (Pressure - Volume)

air rush inside the lungs, inflating them (inhaling). When diaphragm moves up, the

volume of the air inside the bottle decreases, which causes more air pressure inside the

chest cavity and air rushes out, leaving the lungs deflated (exhaling). The breathing

continues as the diaphragm moves in and out.

Balloon aslungs

Big sodabottle

A glove or

balloon as

diaphragm

Most people do not really understand

how we fill our lungs with air, or the

process of breathing in and out. Here is ademonstration of how our lungs work.

Use a big soda bottle as a chest cavity.

Cut open the bottom of the bottle.Tightly cover the bottom with a flexible

material, such as a latex glove or a

balloon. Then, in a similar way, place a

balloon inside the neck of the bottle asshown in the figure. Now when you

move the diaphragm in and out, you will

see the balloon inside the bottle deflatingand inflating. When the diaphragm

moves down, creates more volume for

the air molecules inside the chest cavity.Thus, the air pressure inside decreases,

which makes the outside


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8. Cartesian Diver: Boyles Law (Pressure - Volume)

As you squeeze the bottle, the water moves up in the eyedropper, therefore the

eyedropper gets heavier and sinks inside the soda bottle. As you release the bottle, the

water inside the eyedropper pushed out by the air left inside and eyedropper is mostlyfilled with air again so it gets lighter and moves up. Although the explanation can be

more complex, at 3rd grade level, this observation is the only thing they should

experience. Once they move to 6th grade level, they will receive a more detailedexplanation of Boyles Law.

Water

Sodabottle

Eyedropper

partiallyfilled with

water

The figure on the left is a Cartesian diver. You need an

empty soda bottle, water, and an eyedropper. Fill the

soda bottle with water completely/until it is full. Fill theeyedropper with water as well. Then, carefully place the

eyedropper inside the soda bottle vertically in a way the

plastic head stays up. Then close the lid. You can tellthe students that you know a magic and that you can

make the eyedropper go up and down inside the bottle

by using mind power. Then show them how you dothat. In the mean time you try to squeeze and release the

bottle carefully without getting their attention. They

will figure out quickly that you are actually squeezing

the bottle. Pass the bottle around, or you can provide

more samples of the Cartesian diver to the students.Ask them to make observations. They will soon notice

that the water inside the eyedropper moves up anddown as they squeeze and release the bottle.

sample discrepant events

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