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Water → Focus on Science
Cleaning Water Learning Journey
Introduction
Learners
v could be introduced to how water is treated here in Scotland by watching the introductory video on the
Glencorse water treatment works. They will learn about water treatment processes and the science involved in making
water safe for human use.
They could then be involved in applying skills and learning in the context of an engineering challenge where a water
charity have commissioned them as teams to investigate the problems faced by communities in developing countries
who do not have a clean, safe water supply. The learners are challenged with developing solutions to plan for providing
a given community with one. An example of how this challenge could be presented can be found on the STEM Central
website. This learning context would provide rich opportunities for planning for interdisciplinary learning with other
departments such as technologies.
This learning journey with a sciences focus is aimed at third level. Learners are asked to reflect on the different ways in
which water can become polluted and on the importance to humans of a safe, clean water supply. They are then given
a scenario and a brief for analysing raw water. Learners explore a range of techniques for physically separating
mixtures into their components in relation to the context of cleaning water.
An overview planning sheet is shown on the next page, which gives a plan for learning and teaching starting from the
experiences and outcomes. Learning intentions, success criteria and possible evidence of learning which could be
gathered are shown. The pages that follow the overview give examples of learning experiences which would address
the learning intentions. They illustrate opportunities for learners to develop knowledge and understanding of physical
methods of separating mixtures into their components and provide opportunities to apply relevant skills.
Sciences experiences and
outcomes
I can differentiate between pure substances and
mixtures in common use and can select appropriate
physical methods for separating mixtures into their
components. SCN 3-16a
Responsibility of all areas which
could be addressed inthis learning
journey:
I can independently select ideas and relevant
information for different purposes, organise essential
information or ideas and any supporting detail in a
logical order, and use suitable vocabulary to
communicate effectively with my audience. LIT 3-06a
Interdisciplinary learning planning
opportunities
An engineering challenge related to providing a
clean, safe water supply for a community in a
developing country could provide opportunity to plan
for interdisciplinary learning with other departments.
Possible links
Technologies TCH 3-14a, TCH 3-15a
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Water → Focus on Science
Cleaning Water Learning Journey
Experiences and
outcomes
I can differentiate between pure
substances and mixtures in common
use and can select appropriate
physical methods for separating
mixtures into their components.
SCN 3-16a
Learning intentions
Success criteria
Possible evidence
Understand that polluted water is a
mixture of components
I can explain the differences between
pure water and water that has been
polluted
Recordings of group discussions
Understand the process of
coagulation as a physical method of
separating mixtures into their
components
I can explain what coagulation is
Learners’ explanations of how
coagulation is used in the process of
water treatment
I can investigate the suitability of
different reagents for coagulation
A table of results showing a variety of
coagulants tested and discussions on
their suitability
Prior knowledge
At second level (SCN 2-18a),
learners explore common uses of
water, for example as a solvent,
coolant, heat source. They can
participate in practical activities to
clean different water samples, using
a range of methods such as filtering,
evaporating, use of filter beds.
At second level (SCN 2-16a),
learners explore mixtures of
substances and methods used to
separate them into their constituent
parts on the basis of their observable
properties, for example, particle size,
shape, magnetic attraction.
Evaluate different filtration processes
and comment on their suitability for
filtering different samples of water
I can explain the process of filtration
I can use a range of filtration
techniques
Filtration models built by learners
with written explanations comparing
effectiveness of different models
I can assess the effectiveness of
different filtration techniques
Use practical knowledge to select an
appropriate method of physical
separation of a mixture into its
components
I can select appropriate physical
method(s) for separating a mixture
into its components
I can explain and justify the methods
I used
Photograph diaries presented by
learners showing the process the
groups went through to get the ‘dirty’
water ‘clean’
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Water → Focus on Science
Cleaning Water Learning Journey
Learning experiences:
Engage/explore activies
Introduction
An engage activity could be used to help learners
think about the problems associated with dirty
water. This would allow learners to talk about
their ideas, and develop an emerging
understanding of how water can become polluted.
In a further session learners could explore the
relationship between pure substances, mixtures
and components.
Learning intention
Understand that polluted water is a mixture of
components.
Possible tasks
Possible evidence
Present the learners with a container of ‘dirty’ water.
What might be in dirty water? Working in groups learners
could carry out a graffiti board activity based on the
questions: What is pollution? Where might pollutants that
end up in the air and ground come from? How does water
become polluted? What could be in water that could
cause health problems?
Recordings of group discussions
After writing down their ideas the group decide on a
definition of water pollution to go in the middle of a large
piece of paper. They could also be asked to list the top
five most common suggestions on where pollutants come
from and what might be in water that would cause health
problems. The interactive on the STEM Central website
could now be used to help learners find out more about
how water becomes polluted.
Reflecting on learning
A causes and consequences card sort could be used to
help introduce learners to some of the problems
associated with polluted water. A sheet is provided in the
supporting resources, which can be found on the STEM
Central website, giving information which could be used to
create a card sort.
A further research task could be set for them to
find out more about sources of pollution and
possible health and environmental problems they
can cause.
Learners could now be given an activity where they are
given a sample of pure water and water containing sand
or dissolved solids such as sugar or salt. Learners are
then tasked with evaporating the water using a Bunsen
burner and discussing what they think the dissolved solid
may be and how it affects the purity of the water.
Through discussion, draw out the differences between
pure substances and a mixture containing different
components.
Strategy
o Click here for more information on the graffiti
board strategy.
Before and after – learners reflect on what they
thought in relation to the questions. How and why
did their thinking change?
Taking it further
This context for learning provides rich
opportunities to develop the cross cutting theme of
developing global citizens.
Learners could compare and contrast the differing
situations in a developing and developed nation
using the Water for All activity on Upd8 or an
activity from Water aid education or similar.
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Water → Focus on Science
Cleaning Water Learning Journey
Learning experiences: Explore
Possible tasks
Possible evidence
Introduction
Which coagulant is best?
A range of explore activities are possible to help
learners understand the processes involved in
cleaning water and in physical methods of
separation of mixtures into their components.
After introducing what a coagulant is, learners could be
asked to explore which coagulants are best to improve
the clarity of the water.
As well as investigating the processes the tasks
can be presented in such a way as to allow for
open-ended investigation where the answer is not
obvious and something genuine can be
discovered.
Learning intentions
o Understand the process of coagulation and
investigate different coagulation agents.
o Evaluate different filtration processes and
comment on their suitability for filtering different
samples of water.
The coagulants the learners could be given could
include: aluminium sulphate and calcium hydroxide.
Learners could be given the opportunity to carry out an
open-ended investigation where they select their own
possible coagulants. These could include everyday
products as well as laboratory chemicals. They could
also discuss some of the factors that might make some
chemicals more suitable than others, for example, cost,
environmental impact and effectiveness.
v
Which filter is best?
Groups could explore a sand/gravel filtration process
and a membrane (filter paper) process and use their
findings to decide which filtration system should be used
to purify a given water sample.
If the raw water has had food colour and/or food
essence added, groups could work to eliminate these
factors given sand, gravel, charcoal, and, if available,
activated charcoal, to experiment with. This method
could be compared with a membrane process using
filter papers of varying porosity.
Some practical ideas relating to exploring coagulants
and filtration can be found in the teacher’s notes in the
related resources section.
o Learners’ explanations of how coagulation is
used in the process of water treatment
o A table of results showing a variety of
coagulants tested and discussions on their
suitability
o Filtration models built by learners with written
explanations comparing effectiveness of
different models
What else could be explored?
The process of distillation could be introduced with
learners understanding how this can be used in
separation of a mixture.
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Water → Focus on Science
Cleaning Water Learning Journey
Learning experiences:
Explain/elaborate
Introduction
This activity allows opportunities for learners to
test out their ideas and to apply their learning to a
practical challenge related to a real-life problem.
This activity allows them to work in mixed-ability
groups to select the most appropriate method to
separate a ‘dirty’ water sample into its
components.
Learning intention
Use practical knowledge to select an appropriate
method of physical separation of a mixture into its
components.
Possible tasks
Possible evidence
Learners could be placed in groups and each
presented with a different sample of ‘dirty’ water.
The group will have to apply their previous
knowledge of physical methods of separation to
select the most appropriate method for their
sample, to end up with a sample of ‘pure’ water.
Photograph diaries presented by learners showing
the process the groups went through to get the
‘dirty’ water ‘clean’
Explain that they will be working in ‘research
groups’ to investigate their sample. A ‘pack’ could
then be issued to each group outlining a brief with
a scenario where they are in a particular situation,
such as an area that has been hit by a Tsunami
and the water has become polluted. Possible
available resources could be outlined.
Learners then have to create a plan to clean their
water using an appropriate method(s). They could
then carry out their plan and be prepared to report
their findings with justification of why particular
method(s) were chosen. Groups could create a
photo diary to help them report on findings.
Success criteria could be agreed with the learners
to assess each group’s explanation and
justification of the processes they used.
Taking it further
Through discussion learners could consider
whether the cleaned water is now safe to drink.
This could lead onto investigation of other
techniques for cleaning water. Teacher’s notes are
provided in the supporting resources section on
the STEM Central website on other techniques
which could be explored.
Some suggested techniques are:
o pH
o total dissolved solids using conductivity
o total turbidity using colorimetry (or by eye
comparing to a chart)
o bacterial content by growing cultures
o BOD levels (Biological oxygen demand) using
methylene blue indicator and a ‘colorimetric
determination’ (or by eye)
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Water → Focus on Science
Cleaning Water Learning Journey
Learning experiences:
Explain/elaborate
Introduction
Explain activities allow learners to demonstrate
their new understandings to an audience.
Elaborate tasks allow learners to synthesise and
apply new knowledge. They can be used to help
give opportunities for choice and challenge.
Learning intentions
o Know the processes used to treat raw water in
this country.
o Select ideas and relevant information.
o Communicate findings in a suitable way to an
audience.
Possible challenges
Research how water is cleaned in Scotland. One
possible resource the learners could use is
BBC learning zone clips – How is water cleaned
Use the video to find out about the Glencorse
water treatment works and to hear from some of
the civil engineers who are working on building the
plant.
The following task could be linked to a challenge
where, in groups, learners are asked to report their
findings to a planning authority. Through
discussion they could consider how the civil
engineers working on the Glencorse water project
may have had to work with the local authority
planning group for that area.
Some of the information they could be asked to
include in their report could be:
o explaining the results of their investigations into
coagulants, and reports upon which they would
recommend
o a description of the method they would
recommend for filtration based on their findings
o explaining a technique for analysing water
samples
Responsibility of all
These learning experiences offer an opportunity to
address an aspect of responsibility of all such as:
I can independently select ideas and relevant
information for different purposes, organise
essential information or ideas and any supporting
detail in a logical order, and use suitable
vocabulary to communicate effectively with my
audience. LIT 3-06a
Interdisciplinary learning
The knowledge, understanding and attributes
developed during the learning journey could now
be applied to an engineering challenge where
learners are asked to plan for working with a
community in a developing nation who do not have
access to a clean, safe water supply. This would
provide rich opportunities for planning for
interdisciplinary learning with other departments
such as technologies.
Reflecting on learning
Use the technique, ‘What went well... Even better
if...’ to get the learners reflecting upon how they
did in relation to agreed success criteria.
They should also be given an opportunity to think
about the knowledge, skills and attributes gained
during the challenge and how these relate to the
world of work, in particular the role of civil
engineers.