Learning area: Technology
Level: Years 5 and 6
Filters
1 Nature of the assessment task
Students discuss the importance of clean water around the world, and then reflect on the problems facing a country town where the water is becoming increasingly dirty and unsuitable for use. To assist a family in this community, they are asked to investigate, design and make a model for a water filter, which could be used to filter the water for washing purposes.
The completed assessment task is expected to demonstrate the following qualities:
- an ability to use tools and equipment safely and competently
- an ability to communicate ideas and show creativity and knowledge in an annotated design
- an ability to explain decisions made as a result of investigation
- an ability to meet a design brief
- an ability to critique/evaluate the difficulties in constructing the filter.
2 Links with State and Territory curriculum
3 Prior teaching and learning
For this task, students need to have an understanding of the principles of fair testing.
In addition, students should be able to:
- write a procedure
- annotate diagrams
- make observations and record information
- work safely and responsibly with equipment
- organise equipment
- work both collaboratively in groups and independently.
4 Teacher preparation
Student resources
Teachers will need to provide students with the following resources:
- materials such as sieves or colanders (one per pair of students), containers for collecting filtered water (these could be the same containers that are later used for the filter housing)
- equipment for filter housing
- found materials such as plastic bottles with lid (eg milk, juice or soft drink bottles), plastic containers, etc – one per student + spares. Students should also be encouraged to contribute their own suggestions.
- tools eg scissors, rulers, permanent markers, hammers, nails
- a 2-litre plastic bottle for muddied water mix (one per group of two students), tablespoons (enough for easy access), container of dirt, container of crushed leaves
- materials for filter
- 1 bucket washed gravel (coarse)
- 1 bucket washed gravel (fine gravel – as used in aquariums)
- 1 bucket washed sand (fine)
- 1 bucket washed sand (coarse)
- 3 packs filter wool
- 15 foam sponges
- fabric squares (approx. 30 cm, one piece per group of two students)
- strainers or fine net mesh (one per group of two students)
- Other suggested equipment to assist in the conducting of this activity
- broom/ dustpan /mops/cloths for spillage
- access to tap
- water bowls
- plastic placemats.
The following resources are provided:
Teacher resources
Teachers will need to provide:
The following resources are provided:
Teachers might find it helpful to examine an annotated worksample for the task. Further information about worksamples and how to use them can be found at this link.
5 Scaffolding: Preparing students for the task
The following scaffolding activities are suggested as ones that will prepare students to design, make and evaluate/critique a filtration system.
The scaffolding activities provide opportunities to informally assess for learning and to provide feedback to students on their progress.
Activity One: Letters to the Editor
Introduce students to the Letters to the Editor resource and discuss the problems facing this town.
Explain that fortunately rainwater tanks provide enough water for drinking, but there is a need to filter the tap water so that it can be used for washing purposes.
Introduce the Filter design brief and discuss its requirements.
Activity Two: Identifying different kinds of filter
Show students a number of different kinds of filters, eg a sieve, a face mask, a sink strainer, and ask what the objects have in common.
Ask students, in pairs or groups, to discuss:
- other examples of filters
- the functions of filters
- the kinds of materials that they think are used inside a filter
- how they think filters work.
After discussion, students contribute to a class concept map of different kinds of filters. This could be done on a large sheet of paper and kept for later reference or completed on the chalkboard. (For an example see Filters concept map.)
The concept map should include:
- the filter's function, eg cleaning water in a swimming pool
- speculation on how it works
- speculation on what materials it uses.
Information gathered from this concept mapping exercise could be used to make a class list of the kinds of materials students believe are used in a filtration process.
Activity Three: Investigating filter materials
Show students a glass of water, poured from a 2-litre container that has had a tablespoon of dirt and a tablespoon of crushed dried leaves added to it and explain that this is an example of the quality of the water in the country town about which they have been reading in Letters to the Editor.
Explain to students that first they will need to test a variety of filtration materials to decide which ones will be most appropriate for their filter system.
Explain that the method used will need to be sustainable (eg filter paper would need to be replaced constantly if used for this purpose, given the heavy flow of water).
Distribute and explain the worksheet Investigating filter materials.
Have students work in small groups to discuss the questions focusing on fair testing procedures and to list some of the equipment they will require. Briefly review students' answers as a class.
Ask students to devise a method for conducting the test, and to write the procedure in the space provided on the Investigating filter materials worksheet. If necessary, revise the structure and language features of a procedure text.
Review these ideas as a class, and then collaboratively devise and display a fair testing procedure that all students will use. Add to the equipment list as required.
Investigating
Students work in pairs to test the materials as described in the recording grid located on the Investigating filter materials worksheet.
Show them how to make the standardised muddied water, by placing a tablespoon of dirt and a tablespoon of crushed dried leaves in a 2-litre container of water.
They take turns to use the materials as filters, ensuring all materials are cleaned thoroughly before use. An understanding of the principles of flotation and sedimentation will assist students in completing this activity.
Provide students with sieves and containers to assist in the investigation.
Materials required:
- 1 bucket washed gravel (coarse)
- 1 bucket washed gravel (fine – as used in aquariums)
- 1 bucket washed sand (fine)
- 1 bucket washed sand (coarse)
- 3 packs filter wool
- 15 foam sponges
- fabric (one piece approx. 30 sq. cm per group of two students)
- strainers (one per group of two students)
- any other material as negotiated with the teacher.
They record their results on the recording grid on the Investigating filter materials worksheet.
Remind students that:
- the clean-up will need to include the separation of some materials for use in the task
- no filtration materials should be washed down the sink as this will cause drainage problems
- the Investigating filter materials worksheet will need to be retained so that they can refer to it when making their final filter.
6 The task
Designing
Distribute and explain the Student rubric and revisit the elements of the Filter design brief.
Students:
- produce two designs for a filter housing
- examine and analyse their test results on the Investigating filter materials worksheet to decide the best materials to use in their filter.
They firstly draw their proposed filter models on the first page of the A3 worksheet Filter design, showing:
- the order, type and depth (or number of layers) of filter materials they will use (various filter materials can be combined)
- any changes they have made or propose to make to the filter model
- why they have chosen to use that design, and those materials, in that order.
Note: As students might decide to modify or remake their filter housing, it may be advisable to allow a couple of days between designing and making the models, in order that any extra equipment can be organised. Students should be encouraged to negotiate or organise their own additional requirements.
Making
Students make a model of their filter, based on their design.
They:
- work individually to make their models
- may continue to modify the design of their filter in response to ongoing analysis of the effectiveness of different components(Make–Evaluate/Critique–Make process).
While students make their models, the teacher uses the Group observation sheet to note their progress and to gather evidence to make an assessment of the students' ability to handle tools safely and competently.
Critiquing/evaluating
Students use the second page of the A3 worksheet My completed filter to record their finished design (either a sketch or a photograph), and to explain and reflect on how they changed their model to solve some of the difficulties as they arose and to meet the design brief. Remind students that they should return to the design brief in order to critique/evaluate their design and that they should also comment on the processes that they used to make their model.
7 Professional advice
Teachers could use the following diagnostic grid to record students' performance on each of the expected qualities to obtain a snapshot of those areas in which students will need further instruction. The teaching and learning activities that follow the grid are also related to each of the expected qualities and suggest some ways in which teachers could consolidate or extend student performance. Click here to view how the grid might be completed.
Teaching and learning activities linked to the expected qualities listed in the rubric and the diagnostic grid can be found at the following links:
Teaching and learning activities: Ability to use tools and equipment safely and competently
Teaching and learning activities: Ability to communicate ideas and show creativity and knowledge in an annotated design
Teaching and learning activities: Ability to explain decisions made as a result of investigation
Teaching and learning activities: Ability to meet a design brief
Teaching and learning activities: Ability to critique/evaluate the difficulties in constructing the filter
Teaching and learning activities
Ability to use tools and equipment safely and competently
If safety is an issue, it could be that students have not been explicitly taught safe ways of handling different tools.
Safety rules should be:
- negotiated with the class
- clearly displayed
- referred to before using equipment, and at times of indiscretion
- modelled and practised as required.
Students who continue to disregard safety rules may need to have reduced access.
Use teacher modelling, and student demonstration to develop and reinforce these safe handling skills.
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If students performed at a low level in terms of competently using the tools, it could be because they had not been explicitly taught effective ways of using different tools. Observe and note the tasks or tools that are causing difficulties and find opportunities to explicitly teach or model effective strategies.
For example:
- students who had difficulties dividing the plastic container into two parts, could be shown how to use a saw to make a starting cut
- students who had difficulties making holes in the bottle lid could be given a nail with a larger head, given a tack hammer, or shown how to tap the nail in gently at first
- students who had difficulties hammering could be shown how to hold a hammer for greater leverage and impact.
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Students who perform at a high level on this aspect of the task could be used to demonstrate different strategies or provide assistance. These students could be provided with more challenging materials to use with the tools, or a greater range of tools in another technology task.
Teaching and learning activities
Ability to communicate ideas and show creativity and knowledge in an annotated design
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If students performed at a low level on this aspect of the task, they may need assistance to understand the standard and detail that was required.
Collect examples of different annotated designs for display and discuss how annotations and labels help communicate ideas.
Invite speakers (eg people in the school community) to discuss and show how designs are used in their work – eg builders, landscape designers, dressmakers – so that the students are helped to understand the relevance of this activity.
Encourage students and speakers to talk about how their learning and product can be enhanced through taking risks by trying new innovations or ideas.
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If students performed at a high level on this aspect of the task, they could conduct research (including online) into different kinds of filtration methods, collecting any designs which show how the systems work and the equipment that was used. These diagrams could then be interpreted by writing an explanation of how that filtration system works.
Teaching and learning activities
Ability to explain decisions made as a result of investigation
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If students performed at a low level on this aspect of the task, they may need to review what was discovered in their Investigating filter materials task, and compare their findings to the results of other members of the class.
- Collect class data from the recording grid on the Investigating filter materials worksheet.
- Have it recorded prominently so that the results can be compared.
- Compare results and discuss possible reasons for differences.
- Analyse the relationship between materials which performed best in the filter tests, and the choice of materials in the most effective filters.
- Ask students who performed well on this aspect of the task to explain how their decisions were made.
- Brainstorm familiar examples of when students have made a selection based on identifiable characteristics or performance of materials, eg by testing the performance or colour of felt pens before using them, choosing a particular food because of flavour or a ball because of bounciness.
- When testing to identify the characteristics of materials in other contexts, ask students to articulate their analysis process, and to identify their reasons for making certain choices.
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Students who performed at a high level on this task could experiment with separating other materials.
For examples, refer to the teacher reference Filtering out ideas.
Teaching and learning activities
Ability to meet a design brief
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If students performed at a low level on this aspect of the task, they may need assistance to understand the purpose of a design brief.
- Go through the Filters design brief and discuss possible reasons why each requirement was made.
- Use a familiar task, like making a poster, to negotiate a class design brief.
For example:
- compile a class negotiated design brief for a poster to advertise your filter
- ask students to analyse why certain recommendations (like size of writing) are being made.
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If students performed at a high level on this aspect of the task, they can collaboratively formulate design briefs for topics they have researched. This can assist students to understand the design brief's purpose and to meet its requirements.
Teaching and learning activities
Ability to critique/evaluate the difficulties in constructing the filter
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Students performing at a low level on this aspect of the task may be supported by critical thinking scaffolds such as a Question matrix.
Students work in small groups, taking turns to present their explanation about the kinds of difficulties they encountered when building their filter. In some situations, where no difficulties have been identified, it may also be useful to provide pictures of the original design and the completed model so that the group can discern whether any changes have been made. The group members are then invited to each ask a question of the student who wrote the explanation, to help them articulate more detailed information about the types of difficulties they encountered or the reasoning that helped the student to formulate a solution.
The Question matrix can be used to guide the students in formulating their questions. For example, questions could be devised seeking reasons 'Why would the cloth be better placed under the sand?'; 'Why did coarse sand create problems?'; or seeking means: 'How can double layering the cloth improve its ability to filter?'.
Students can then choose one or two of their answers to add to their original explanation.
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Student work that indicated a high level of critiquing/evaluation could be used in an initial whole class discussion to introduce the Question matrix activity. The class could try to formulate possible questions, using the matrix as a guide, and which the given explanation already answers.
For example: 'Why did you choose masking tape over sticky tape?'.
Those high achieving students could also be questioned about other changes they may have made to their model, and why they considered those changes necessary.
For example: 'Why is the Chux cloth used at the top of the housing, instead of the stocking shown in your design?'. This will model the process that is to be used, using students who have shown some successful critiquing skills as role models.
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