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C U R S O D E P R O F E S S O R E S D E E D U C A Ç Ã O B Á S I C A

D O C E N T E : A N T Ó N I O A L B E R T O S I L V A

F Í S I C A P A R A A E D U C A Ç Ã O

R E L A T Ó R I O D E A L U N O S

PAPER PHYSICS EXPERIMENTS

Alunos:Sofie DhondtSofie Van Royen

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1. Introduction

Science in primary education is not focused on the theory, but the principal is to let the

children discover, experience and handle.

Our experiments are focused on the handling, experiencing and discovering.

We also want to highlight different aspects of physics. Like fire, water, electricity and

light. In addition they are easy to perform with less material, which is simple to do in

primary school.

The experiments we discuss below have been adjusted to the level and environment of

the children. We find it important that the children learn to discover experiments that

deal with questions in the daily lives and that they also may encounter.

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2. Experiences and their physical interpretation

EXPERIMENT 1: Pepper and salt

You use Pepper and salt in your food for a little more taste. If once you've mixed them together, it’s difficult for separating the pepper and salt again. Or maybe not?

Duration of the experiment : 10 minutes

What do you need for the experiment? - Pepper- coarse salt - woolen sweater - balloon - table

Follow these steps: 1. Blow the balloon and tie it close.2. Sprinkle some salt on the table.3. Sprinkle some pepper on salt.4. Rub the balloon on your hair or your sweater.

Question 1: What do you think will happen when the balloon put above the pepper and salt means?

5. Hold the balloon 5 cm above the pepper and salt.Question 2: What happens? Question 3: Why is this possible?

Explanation

Answers on the question:Question 1 All answers are good. It is a question for them in advance what you think.

Question 2 The pepper will sit on the balloon, the salt stays on the table. If you come very close to the balloon then the salt sit on the balloon.

Question 3 If you rubbed the balloon on your sweater, the balloon will be charged electrically. The pepper feels that. That’s why the pepper wants to stick on the balloon. The pepper grains are small and light. The salt grains feel the pull of the balloon too, but they are larger and heavier than the pepper grains. The gravity pulls closer to the salt grains than the balloon does. Gravity wins the attractiveness of the balloon. The salt stays lying on the table. If the balloon comes very close to the salt grains, the attractiveness will win of the gravity and the salt will stick on the balloon too.

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Extra explanation

When the balloon rubs on your hair or on your sweater, the balloon will be charged electrically. The balloon is negatively charged. This charge is called static electricity, because this charge is not flowing but the charge remains on the balloon. There is positive and negative charge.

Opposite charges attract each other and equal charges steric forces. Pepper and salt are not loaded. This means that there are as many positive as negative charge in the grain. The negative charge is disposed by the balloon and will be sitting far from the balloon in the grains. The positive charge is attracted by the balloon and the balloon will sit close in the grains. The force of the positive charge of the grain is attracting more than just the power that the negative charge of the grain pulls away. This is because the positive charge of the grains is a little closer to the balloon then the negative charge. This attraction is strong enough for the peppercorns to lift and not strong enough for the salt grains to lift. Except if the balloon comes closer to the grains.

For this experiment, it’s important that there is a real difference in size of the grains between the coarse salt and fine pepper. If you do not have this at home you can also do the experiment with, for example sugar. The grains remain electrically neutral, because there is equal postitieve and negative charge in the grains. The charge shifts within the grains.

More physical explanation:

Electrons:All objects are composed of atoms. Each atom consists of a very small core, nucleus. The core consists of 2 types of particles:

o protons positiveo uncharged neutrons

This core is surrounded by one or more electrons. In a neutral atom, there are as many protons as neutrons. If the balance is disturbed, then we speak of a charged atom.

An atom consists of a positively charged nucleus surrounded by electrons. For some substances, the outer / inner electrons can move freely. These electrons can move freely in the solid. Therefore we call these electrons, free electrons.

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EXPERIMENT 2: egg in the bottle

A hoop has a large hole where you can easily pass through. A needle has a very tiny hole and you are far too large to go throught the tiny hole. Still, can you put sometimes big things (automatically) through small holes?

Duration of the experiment : 10 minutes

What do you need for the experiment? - hard boiled egg- bottle with wide neck - matches - an adult

Follow these steps: 1. Peel the hard boiled egg.2. Put the bottle on the table.3. Put the egg in the bottle.

Question 1: Can you push the egg into the bottle? 4. Take the egg back on the table. 5. Ask an adult for three matches to stabbing.6. Ask an adult to put the burning matches into the bottle.7. Put the egg in the bottle with burning matches.

Question 2: What happens now? Question 3: Why is this possible?

Explanation

Answers on the question:

Question 1 Because the egg is larger than the opening in the bottle, the egg can not pass through.

Question 2If it’s good, the egg goes itself in the bottle.

Question 3Everywhere around us is air. The air around you is pushing against you. So the air pushes also on the egg. The fire from the matches warms the air in the bottle up. Warm air presses harder against everything than cold air. In the experiment you put the egg on the bottle with warm air. The air in the bottle cools down, that’s why the air is pushing the egg from outside into the bottle. You can also say that the egg is sucked from inside.

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Extra explanation:

The matches in the bottle are making the air very warm. Then you close the hot air in the bottle with the egg. And for each combustion you need oxygen. Because the oxygen burns out and no new air can come in, the matches will go out.

If the air cools down, the pressure in the air goes downs too. This is because cold air takes up less space than hot air. Because the pressure in the air outside of the bottle remains the same, there is a pressure difference between inside and outside the bottle. The pressure difference makes the egg pushing in the bottle is ( if you look from the outside), or in the bottle sucked, (if you look from the inside).

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EXPERIMENT 3: attractive balloon

A balloon is very useful. You can attract things to you without even touching!

Duration of the experiment : 10 minutes

What do you need for the experiment? - balloon - crane (water)- sweather

Follow these steps:

1. Blow up the balloon.2. Rub the balloon on your sweater.3. Put on the crane.4. Ensure that there is a small trickle of water from the tap is running.

Question 1: What do you think will happen when you hold the balloon against the water?

5. Hold the balloon near the trickle of water, make sure that the balloon is not in the ray of water.

Question 2: What happened to the trickle of water?

Explanation:

Answers on the question:

Question 1 All answers are good. It is to this question for themselves in advance what you think.

Question 2 If you rubbed the balloon on your sweater, the balloon becomes electric, like a battery. The water from the tap feels that. That’s way the water wants to go to the balloon.

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Extra explanation:

When the balloon rubs on your hair or on your sweater, the balloon will be charged electrically. The balloon is negatively charged. This charge is called static electricity, because this charge is not flowing but the charge remains on the balloon. There is positive and negative charge.

Opposite charges attract each other and equal charges steric forces. Water is electrically neutral. However, each water molecule is on one side a little positive and a bit negative on the other side.

That’s why, in the electrically neutral water the negative side of the water molecules will be rejected by the balloon and it will go so far from the balloon into the trickle of the water, and the positive side of the water molecules are attracted and close to the balloon into the trickle of the water.

The force that pulls on the positive side of the molecules, is slightly stronger than the force that pulls away the negative sides of the molecules, because the positive side of the molecules is slightly closer to the balloon then the negative side. The force is strong enough for the water to bend.

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EXPERIMENT 4: Make a rainbow

It is not often that you see a rainbow. Maybe you feel too bad, because it has so many beautiful rainbow colors. But you can also make a rainbow! Some children play in the summer under a washer in the garden. If the water from the nozzle comes in the sunshine, we can see a rainbow too.

In this sample you can make a rainbow, inside home!

Duration of the experiment : 5 minutes

What do you need for the experiment? - a sunny day- glass of water (preferably a long and high glass)- a white paper

Follow these steps:

1. Put the glass of water so that there is quite a lot of sunlight on.2. Wait until the water no longer moves.3. Move the white piece of paper around the glass of water and try to catch a rain arc.

Question 1: When do you see a rainbow?Question 2: What happens when you take an other glass with a different form?

Explanation:

Answers on the question:

Question 1 You see a rainbow on the white sheet of paper when the sunlight go through the glass of water and falls on the paper. So the sun is behind the glass and the paper is in front of it.

Question 2 With a glass of a different shape, the rainbow gets also another form.

Sunlight and white light are really “all-color light”, this means: all colors are in it. If you see all colors at the same time, you see white! Water can tear the colors apart, so you can see them separated from each other. Then you see a rainbow. You can see this only when the light goes through the water. This is also the way how it works with a rainbow too. You can only see the colors when the sunlight goes through the rain. The shape the glass determines how the colors are drawn apart and what form the rainbow will have.

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Extra explanation:

Sunlight and other white light consists out of all different colors together. Light has different speeds in different media. This has the effect of how the light deflects (breaks) if it goes from the one to another medium. (From air to water) Different colors have slightly different speeds and that’s why they deflects on a different way (another angle), which makes the colors tears apart, the color from each other. We can see now the different color lights separated. We can see a rainbow.

By sunlight: By flashlight:

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EXPERIMENT 5: Paper under water

You become wet of water! For example you will be wet when you go swimming or if you go in the shower. The paper of a book may not be wet, that’s why you can’t read a book in the shower. The pages would be soaked! Or can it?

Duration of the experiment : 10 minutes

What do you need for the experiment? - a sheet of paper- a glass- a bucket full of water

Follow these steps:

1. Make a plug of the sheet of paper.Question 1: You think the paper will be wet when it

goes under water?2. Put the paper in the glass.3. Hold the glass upside down and push the glass under water.4. Take the glass back above the water and take the paper out of the glass.

Question 2: What happened?Question 3: How do you think that this is possible?

Explanation:

Answers on the question:

Question 1 All answers are good, if you wrote what you thought what would happen.

Question 2The paper in the glass remained dry under water.

Question 3 All answers are good, as you wrote how you thought it was.

In the glass is paper and air. In the water will air always go up. But the air can not go through the glass, so it’s stuck in the glass. The paper remains dry. There can’t come water in the glass because it’s already filled with all air. When you doesn’t keep the glass right up, the air will escape and the paper will get wet.

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Extra explanation:

First you can explain to the children or they already had some experience with air in water. You can give some examples as diving, bubble bath,... In this way, you can show them easily that the air wants to escape out of the water. It always goes up because the pressure of the air is bigger than the pressure of the water.

The reason is because one liter of air is lighter than one liter of water. That’s also why you feel some pressure when you push the glass down in the water. This is because the air wants always going up (out of the water). You can also say that the density (ρ = m / V) of air is smaller than the density of water.

But in this experiment, the air can’t go up because the glass is around it. As long as the air is in the glass, the paper remains dry because the glass is filled with air. If you hold the glass tilted, the air does escape and the paper will be wet!

Conclusion: Where air is, can’t be anything else. The air takes a specific place in space.

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3. Didactic reflection

At first, we go to work with the children to experience a challenge; we do this on the

basis of a specific question. The teacher plays an important role, namely to guide the

experiment and the conversation of questions, particularly that the children

themselves explore.

In every step we explain how you perform the experiment. On the basis of targeted

questions to clarify the children of the experiment. After perfoming the test, the

children compare their predictions with the end result, and that will clarify the

explanation of the experiment.

There is a small discussion between the students where the teacher sends them to the

correct answer. Afterwards the teacher gives some theoretical explanation at the level

of the children.

We also find it very important that the experiment is first classical and then

individually in smaller groups so they can further explore, experience and handle by

themselves.

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4. Bibliography of the experiments:

1. Electricity: pepper and salt- http://proefjes.nl/uitleg.php?nummer=130&categorie=elektriciteit- http://tdeckers.classy.be/Cursus/WW/04Les01CursusLln.pdf

2. Fire: an egg in a bottle- http://proefjes.nl/proef.php?nummer=84&categorie=vuur- http://www.kippengrabbelton.be/junior/proeven/proef1.htm

3. Electricity: static electricity with a balloon- http://proefjes.nl/proef.php?nummer=66&categorie=elektriciteit- http://members.shaw.ca/len92/static.htm

4. Light: a rainbow- http://proefjes.nl/proef.php?nummer=35- http://opticalillusion.wordpress.com/2008/07/21/how-to-make-a-rainbow-at-

home/

5. Water: keep a paper dry under the water- http://proefjes.nl/proef.php?nummer=60&categorie=water- http://home.scarlet.be/~gembahem/natuurwe.htm

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