|
|
Name:
|
Category: Physics: propusion/buoyancy water
|
|
|
For
age range: 6- 10 years
|
For
how many?: 5- 10 children
|
|
|
Where: Demonstration room or in the open
|
How
long: ca
20 minutes
|
|
|
Aims
for the children:
The children can see which materials float
and which do not.
Tell the children to put the materials carefully
onto the surface of the water so that they can test even heavy materials.
|
Preparation/materials:
Different objects and materials from the
sphere of experience of a child, such as: buttons, polystyrene, toothpick,
drawing-pins, cork, plasticine, toy pieces, water, bowls, etc.
|
|
|
Scientific
background:
Whether any object floats or not depends on
the relation between buoyancy and weight. If you immerge an object into water
different cases may occur:
Buoyancy < weight = The body sinks.
Buoyancy = weight = The body floats.
Buoyancy > weight The body rises to the
surface and floats.
For solid and compact bodies (such as a
wooden ball, a solid rubber ball, cork, etc.) it is the density of an object
(i.e. how many grams is a cubic centimetre of a body) compared with the
density of the liquid which determines whether an object floats in the liquid
or sinks. If the density of the material is lower than the one of the liquid
the body floats.
Another factor playing an important role for
many floating bodies (such as ships, balls, empty bottles, etc) is their
form. It is decisive that bodies displace much water when immerging into the
water without any intake of water. The same applies to the experiment
described above: the plasticine boat displaces a considerably larger quantity
of water than any plasticine ball consisting of the same material.
|
Steps:
Once the bowls are on the table the children
can take the different materials and put them onto the water to see which
materials float and which do not.
It is possible to proceed in a
problem-oriented way, for ex. how do I manage to make plasticine float (by
modelling the plasticine ball into a boat).
|
|
|
Possible
variations:
Tell the children what we intend to do: today
is a great day for swimming and diving. We want to test which objects float
and which sink. Prepare two or three bowls filled with water and put them on
a table or outside on the floor.
The children can build polystyrene boats and
see whether they float. If yes, they can charge the boats with weight and see
when they sink.
|
|
|
References:
http://www.physik.uni-kassel.de/did/gs/Schiff.htm
Carolin Schneider & Bastian Fleck
Spannende
Experimente von Herrmann Krekeler und Marlies Kieper- Bastian. Ravensburger Verlag.
|
|
|
Be
aware of:
On the surface of the water there is a film holding lighter objects on the
surface of the water.
|
|
|
In detail:
|
©http://www.physik.uni-kassel.de/did/gs/Schiff.htm
|
|
|
Name:
|
Category:
-
Physics
-
Propulsion/movement/mechanics
|
|
For age range:
4-10
years
|
For how many?:
4
children
|
|
Where:
Tiled room
|
How
long:
ca. 20- 30 minutes
|
Preparation/materials:
Balloon, straw, boards of polystyrene, two
kebab skewers, toothpick, scotch tape, water colour, scissors, knife, paper
Before starting the polystyrene boards are
cut to a smaller size.
|
|
Aims
for the children:
-
The children learn the principle of
repulsion.
-
They learn that polystyrene floats.
-
They learn how to make a boat from simples
materials.
|
Steps:
1.
Cut out the actual boat figure (triangular in
front, rectangular at the back, the top piece is cut out as a rectangle),
2.
the two boards are attached on top of each
other by means of toothpicks,
3.
cut out one sail and attach it to a kebab
skewer.
4.
The balloon is inflated once at the
beginning, then the straw is inserted into the balloon in a way that ca. 3 cm
are still sticking out, attach it with scotch tape.
5.
With adhesive the straw is attached to the
kebab skewer.
6.
Then the boat can be launched.
|
|
Scientific background:
The
air escaping from the balloon has a propulsion effect causing the boat to
shoot ahead.
The air is pressed out of the balloon since
the stretched rubber contracts again.
The air which now comes out quickly pushes the
balloon forward (repulsion).
Repulsion is a force exerted onto a body from
which a mass is repelled or emitted. (cf. Meyers großes Taschenlexikon).
|
|
Be
aware of:
Before starting the
experiment the balloon has to be inflated to make this process simpler.
Make sure that
there is absolutely no air leak between the straw and the balloon.
To make the
inflating process simpler for the children take out the balloon with the
kebab skewer.
|
Possible variations:
The balloons can be taken off the boat together
with the kebab skewer so that the boat can float on its own. In addition, the
body of the boat can be cut out in different shapes, it does not have to be
always rectangular.
|
|
References:
Variation
von:
Sachunterricht konstruktivistisch be-greifen, Band
1, Schneider Verlag Hohengehren 2001
|
|
|
|
|
In
detail:
|
|
Name:
|
Category:
-
Physics
Mechanics
|
|
For age range:
4
to 6 years
|
For how many?:
4
children
|
|
Where:
Tiled room
|
How
long:
ca. 30 minutes
|
Preparation/materials:
Peel the orange the day before without
damaging the peel.
A few hours later the boat needs remodelling.
Blow out the eggs.
Nails,
orange peel, tea lights, blown-out eggs, scotch tape
|
|
Aims
for the children:
The children learn that water evaporates when
heated up.
They learn that orange peel floats.
They learn to handle fire, eggshell and
orange peel carefully.
|
Steps:
1.
Insert the nails into the orange peel in a
triangular form so that you can put an egg on top of them.
2.
Place the tea light in the centre of the
bowl.
3.
Stick up one hole in the egg on one side and
fill the egg with water.
4.
Place the egg onto the nails so that the open
hole is facing backwards (not into the direction of travel).
5.
For decoration purposes you can cut out sails
and rudder from paper.
|
|
Scientific background:
After lighting the candle the water inside
the egg (boiler of the boat) starts boiling and a steam jet shoots out. The
steam expands and escapes under large pressure backwardly from the open
nozzle. It drives the boat in a countermovement. According to the law of the
British physicist Isaac Newton (1643-1727) every movement causes a countermovement.
|
Possible variations:
Your can make the same experiment with
smaller and larger eggshells and/or smaller and larger orange peel.
It is important to test the floating
capabilities of the orange peel and the eggshell before going into the
experiment with the children.
|
|
Be
aware of:
The orange peel has
to be large enough to really float and not sink.
The egg must not be
positioned directly onto the tea light so that the latter is not
extinguished.
|
References:
Sachunterricht
konstruktivistisch be-greifen, Band 1, Schneider Verlag Hohengehren 2001
|
|
|
|
|
Name:
|
Category:
Chemistry
Lye and acids
|
|
For age range: Girls/boys
of age group 5 years and older
|
For how many?: 4-6
children
|
|
Where:
In the wash room or group room with large tub
and wax cloth to lay out
|
How
long:
Ca. 15 minutes
|
Preparation/materials:
Cut the cork into slices of the same size and
thickness. Fill water into the basin (washroom) or into a tub (group room,
lay out a wax cloth underneath the tub); supply pipette, washing-up liquid,
oil and knife; cork cut into slices, knife, water basin filled with water,
washing-up liquid and oil pipette
|
|
Aims
for the children:
The children shall recognise the effect of
flowing-out oil/washing-up liquid and derive a possibility of locomotion.
|
Steps:
- Cut a notch into the
cork discs so that you produce a canal from the first third of the cork
disc to the back end.
- The cork is launched
into the water at the right side of the basin/tub.
- Washing-up liquid is
filled with a pipette into the canal of the cork disc (one drop is
sufficient).
- Observe and analyse
the reaction.
- An second cork disc is
set moving by means of oil (repeat steps 3 and 4). Start a race with
additional cork discs. Which propulsion is faster?
|
|
Scientific background:
Since both liquids used for propulsion
purposes do not (oil) or only partly (washing-up liquid) mix with water and
also present a different density than water they benefit from the surface
tension of the water. Since in the canal of the cork disk they only have one
direction to flow out (action) the cork is pushed forward due to the flow-out
movement (reaction).
|
Possible variations:
Other materials, such as paper and cardboard,
are also suitable for a fast start of the experiment. Use different liquids
to underline the effect and/or illustrate any particular features. See also
the experiment what mixes with water? The construction/design of racing
boats would make the experiment last longer and could reinforce the effect of
the experiment onto the children in a more sustainable way.
|
|
Be
aware of:
Allow only trained and careful children to use
the knife. Alternatively, paper or cardboard can be cut with scissors.
|
References:
Erstaunliche Experimente aus dem Orbis Verlag,
München 2003
|
|
|
|
|
Name:
|
Category:
Physics
Electrics (magnetism)
|
|
For age range:
Girls/boys of age group 5 years and older
|
For how many?:
|
|
Where:
At handcraft table
and/or wash room
|
How
long:
ca. 15 minutes
|
Preparation/materials:
Supply a tub with water as well as some splash
protection. Alternatively, the experiment should take place in the wash room.
All other materials are equally provided.
Paper, nails, paper clips, bar magnet
|
|
Aims
for the children:
The
aim is to understand the links between different experiments.
|
Steps:
- Take the paper to fold a boat.
- The boat is charged with nails and paper clips.
- The boat is launched onto the water and directed by means of the magnet
without having it get stuck at the side of the tub.
- As an aptitude test in agility a race can be started.
|
|
Scientific background:
The nails and paper clips containing iron are
attracted by the bar magnet. When attached to the boat or wedged tight with
the boat they move with the paper boat towards the magnet. This shows the
effect of magnetic force of attraction.
|
Possible variations:
Different materials for the boat. Racing
course on which the magnet is led under water.
|
|
Be
aware of:
Quite safe
|
References:
Dröse/Weiß:
Versuche im Sachunterricht der Grundschule, Auer Verlag Donauwörth 2002
|
|
|
|
|
In
detail:
© Dröse/Weiß: Versuche im
Sachunterricht der Grundschule, Auer Verlag Donauwörth 2002
|
|
Name:
|
Category:
Physics
Mechanics
|
|
For age range: 5-6 years
|
For how many?: 12 children
|
|
Where: Group room
|
How
long: ca 60 minutes
|
Preparation/materials: boards of polystyrene, bricks, stones, two water
basins filled with water
Two tables are equipped with a protection for
handcraft activities.
Put one water basin on each table and fill them
with water. The bricks and stones are placed in a box near the tables.
|
|
Aims
for the children:
The children shall be familiarized with the
feature of balance.
The children shall get a feeling for different
weight.
|
Steps:
Introduction:
We
ask how to charge boats without having them capsize.
We
go to the worktables.
Execution:
The
children make the experiment by loading the polystyrene boards with bricks
and stones.
End:
We
discuss the result. Why did some boats sink, why did they capsize and why did
the bricks stay on the boat.
|
|
Scientific background:
Balance can easily
be explained by using the example of a beam balance. The side where the
material with the heavier weight is placed will incline. See over
|
Possible variations:
Use different materials to charge the boats.
Use different boards, for ex. wooden boards,
plasticine
|
|
Be
aware of:
Be careful with too
large quantities of water since the experiment takes place in the group room.
|
References:
Experiment aus der Praxis
Balkenwaage
Informationen unter:
www.uni-tuebingen.de/uni/pki/skripten/V1_10A_Waage.DOC
|
|
|
|
|
In
detail:
In a beam balance the gravity centre of the
rods is situated below the centre of oscillation. If different weight is put onto
a balance the gravity centre shifts until the torque of the load is evened
out by the torque of the gravity centre. The balance of the torques shows
which parameters have an influence on the sensitivity of the balance.
|
Formula
|
Explanation
|
|
|
Left
|
Torque
|
|
|
Right
|
|
|
Rods
|
|
|
Conditions
for balance
|
|
|
|
|
Sensitivity
of the scale
|
Derivation of the equation in regard to the
sensitivity of a beam balance
|
©
www.uni-tuebingen.de/uni/pki/skripten/V1_10A_Waage.DOC
|
|
