Water experiments - Germany

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Pupils of St. Marien-Schule in Moers / Germany experiment with water.

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Experiments March 2013 Germany Comenius-Project 2012-2013 Water in our Lives

Experiments with water:

Experiments with water Evaporation Optical refrection An experiment with a glass of water Surface tension

1. Evaporation:

1. Evaporation Class 1 Back to overview

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What makes water evaporate ? Setting: We take a wet flanel and wipe our black board . Now we discuss how to get the blackboard dry again . Children have some ideas : Wiping with a dry flanel We are too impatient ! How can we fasten the project ? Just waiting ( normaly next schoolday the blackboard will be dry).

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idea : we fawn with a paper and produce some wind, like the wind in summer drying the washing ! Puh, that is exhausting !!! idea : Turn on the heating This could work as water evaporates faster when it is warm. But we don‘t want to sweat and wait that long . What makes water evaporate ?

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idea using idea1 and idea 2 We take a hair dryer and blow -dry the blackboard . Yeah , that works !!! But why ? What makes water evaporate ? Water evaporates when it is getting warm. The hair dryer blows the humid air away , so „dry“ hot air can absorb new evaporating water .

2. Optical refrection:

2. Optical refrection Class 1 Back to overview

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Optical refraction We need : 1 glas, water , 1 coin We put the coin on a table and put a glas above. We pure some water in the glas Upps , where is the coin gone ? We can see the coin from above. ?

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Optical refraction We can see the coin in case there is only air in the glas, but we can‘t see the coin from the side in case there is some water in. Children try to understand and come along that water seems to be some kind of fence for the light . But why do we see the coin from the top but not from the side ? Some children have glasses and know that these make the light ray go a little different, perhaps this is happening as well with the light ray coming from the coin going through the glass and water . !

3. Experiment with a glass of water:

3. Experiment with a glass of water Class 3 Back to overview

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Experiment with a glass of water ? We need : 1 glas, water , peace of paper We fill the glass wit water. We cover the glass with a piece of paper (not much bigger than the glass) ? We turn the glass, whilst pressing the paper on the glass. We release the paper and … … the paper sticks to the glass.

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Explanation There are a couple of concepts at work in this experiment. The first has to deal with pressure and… … the second has to do with surface tension. The air pressure presses the paper on the glass ! The other is a little difficult to explain , but see the experiment of class 1 about surface tension

4. Surface tension:

4. Surface tension Class 1 Back to overview

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Surface tension We need : a soup plate , water , pepper , washing-up liquid Step Pour water into the soup plate Step Shake some pepper onto the water. Step Dip your finger it into the pepper and water. Nothing happens !

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Surface tension Step Put a drop of washing-up liquid on your finger and dip afterwards with this finger into the pepper and water The pepper rushes to the outer edges of the plate ! Why ?

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An invisible thin skin lies on the water surface, as the water particles stick together very tightly. Rinsing agent destroys this skin. Pepper lies on this invisisble skin. The damage of the skin starts from the place the finger dips in. That is the reason why the pepper “runs away “ to the outer edges of the soup plate. In case of not as much detergent a stabil ring of pepper is formed. Otherwise the pepper will think to the bottom. This experiment shows us how water is contaminated if we add even such simple chemicals! Surface tension

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