Observing the ice

Type of resource: website

Web address http://bressanini-lescienze.blogautore.espresso.repubblica.it/2010/02/05/il-ghiaccio-trasparente/

Language: English, italian

Description

Exploring the concept of opacity in ice through group activities

Scientific concept introduced

Density, liquid, collaborative learning, opacity, purity, impurities, salts, water, transparency, ice, solidification

Creative and critical thinking

Critical thinking:
– Analysis
– Observation
– Reflection

Creative thinking:
– Curiosity
– Astonishment
– Surprise

Mathematical reasoning

Observation and reflection

Scientific thinking

– Asking questions
– Making predictions
– Experimenting
– Analysing results

Learning how to learn

Carrying out an experiment
Investigating the purity of a liquid
Discussing the experiment, drawing conclusions and documenting it

Listening and following instructions
Collaborating in a group
Observing in a scientific way

Additional

– Knowing how to work in a group
– Making joint decisions
– Listening
– Understanding

Observing the ice

Overall aims

allow pupils to explore the purity of liquids
enable pupils to explore the solidification behaviour of more and less pure water
developing pupils’ ability to listen, carry out instructions
developing pupils’ ability to organise themselves and work in groups
developing pupils’ observation skills
observe the different degree of transparency of the ice obtained
developing pupils’ ability to document their work
stimulating group cohesion and positive relationships between pupils

Vocabulary – keywords should be understood

liquid, collaborative learning, water, transparency, purity, impurities

Expected learning outcomes (operational aims)

the child/student will be able to:
– Carrying out an experiment
– Investigating the purity of a liquid
– Discussing the experiment, drawing conclusions and documenting it

the child/student will have developed the ability to:
– Listening and following instructions
– Working together as a team
– Scientific observation

STEM skills – to which the learning unit is related to

CORE STEM SKILLS

Making, conducting a scientific experiment
Observing and forecasting
Investigate
Asking questions
Analysing the results of an experiment
Observe, see, the aesthetic result of an experiment

ADDITIONAL SKILLS

Making joint decisions
Coordination
Listening
Understanding

Teaching methodologies/activity outline

Introduction:
The children/young people are shown the material they will need to carry out the experiment. Talk to the children about water, its properties and transformations.
We are going to do an experiment called: “Observing the ice!”.
The experiment will serve to better investigate purity in liquids.

Activities:
The teacher explains the experiment to the pupils. The teacher then divides the class into small groups. Each group is given different solutions (e.g. distilled water, sparkling water…) for the experiment. She then asks the pupils to work in groups. Each group will use its own material.

Material:
Tap water, commercial sparkling water, de-ionised water such as ironing water, popsicle moulds, freezer, stove, small saucepan, cling film for food storage.

Instructions:
Phase 1
Take the popsicle moulds and fill them with tap water and sparkling water. Then take the deionised water and heat it in the small saucepan until it is almost boiling, i.e. bubbling.

Phase 2
Allow the boiled deionised water to cool and then pour it into the popsicle moulds. Cover these moulds with cling film to prevent impurities such as powder from settling on the water.

Phase 3
Wait for the icicles to form and then take them out. You will notice that the most opaque ones are those formed by carbonated water, while those formed with tap water will be less opaque, and those generated by boiled deionised water will be almost transparent.

Phase 4
We move on to the explanation of this different behaviour. The more impurities there are in the water, the more opaque the ice we obtain. Carbonated water is the most impure because, in addition to mineral salts, it contains large quantities of dissolved gas: it is rich in dissolved carbon dioxide and the ice lolly formed is completely opaque. Tap water produces less opaque icicles because the dissolved gas is not present as an impurity. Popsicles made from boiled deionised water are the most transparent because the water contains no mineral salts and the boiling process has further removed any dissolved gases. It can be seen that the residual opacity tends to concentrate towards the centre of the icicle where fractures can also be observed. This is because the solidification process occurs from the outside in. The liquid water is trapped towards the centre of the ice and as it solidifies, it increases in volume, causing the ice to break. – Step 5 Pupils can be asked to repeat the experiment by changing a few points. For example, they can see the difference between icicles made with boiled and unboiled deionised water. Similarly, they can see that ice lollies made from tap water which has been previously shaken in a cocktail container produce more opaque ice lollies than when it has not been shaken, because the shaking makes it easier for the air in the water to mix. You can also add table salt to the water (whatever it is) and see how the opacity of the ice lollies produced increases with the amount of salt dissolved. You can then go on to ask the pupils whether they expect a frozen lake to be clearer than the ice fields at the North Pole. In fact, there are lakes in Sweden where the water is so pure that when it freezes you can see fish swimming under the ice sheet, which is about 10cm thick.

Conclusions:

At the end of the experiment, the teacher proposes that each group take photographs of the experiment to document the activity and, if necessary, prepare a poster. After discussing the experiment with the teacher, each child in his or her group should document the experiment in his or her notebook. The activity, “Observing ice!”, can be a starting point for proposing other activities/experiments to the pupils concerning the properties of physical transformations of a liquid or for proposing interdisciplinary activities.

Assessment of learning

It takes place through observation by the teacher.

Equipment and materials to be used in learning unit (tools, ingredients etc)

tap water
commercial sparkling water
de-ionised water (such as you use for ironing),
icicle moulds
freezer
stove
pot
transparent film for food preservation
optional: camera and poster to document the experiment.