Surviving on an Island: A Water Filtration Exploration
1. Background
Typical lab experiments fail to facilitate one of the main concepts of science
experimentation and engineering design, that of repeating and improving the experiment or
design after gathering results. Students are often exposed to “canned” labs in which the results
are known ahead of time. They are also often led in the lab explicitly by the instructor, or by a
step-by-step procedure. This severely detracts from student excitement and fails to provide
students with the fundamental engineering idea of testing and improving a solution or design.
These labs also inhibit creativity and prevent students from learning from their mistakes. This
presents the perfect opportunity to implement a two-period engineering design laboratory.
Hands on projects have been shown to increase information retention. Additionally, by
creating a hands-on activity, students get to physically see science and engineering as opposed to
reading about it in a textbook. Another key aspect to hands-on activities is they can be
developed such that the activity is relevant to the student. This societal connection provides a
foundation for a student’s intuitive science skills to develop.
2. Activity Description
Activity Overview:
As a hands-on exploration, students will be teamed up with three peers, who are
“stranded” on a remote island with only the given supplies. Additionally, the only source of
water is from a murky, contaminated source.
To simulate being stranded, three distinct “survival boxes” have been created, with each
one guiding students towards a specific water filtration technique. This “guided inquiry activity”
will permit only minimal inter-team collaborations from forming, without hindering student
creativity.
The focus of this lab exploration is not only learning about water filtration, but also about
the elements of the engineering design process. By giving students two opportunities to test their
filter, they will be able to revise and improve upon their original design. This often overlooked
aspect of engineering design is crucial to experimentation, as experiments rarely work correctly
on the first attempt.
Day 1: Engagement and Introduction to Engineering Design (1:15)
As an introduction into the two-day lab, several clips of the Discovery Channel’s
Survivorman series will be shown to students. These clips will show Les Stroud (Survivorman)
in several different survival scenarios in which he must find a source of clean water to survive.
He only has a multi-tool, camera equipment, and whatever the producers may have left for him.
Using only the random items and what Les Stroud can forage, he must find (or create) a source
of potable water. These clips provide the underlying foundation for the lab experiment, as
students will be required to create a water filter using only the materials given to them in their
team’s particular “survival” situation.
After the engagement, students will learn the basic aspects of the engineering design
process (Figure 1). Students will have time in-class to go through the first seven parts of the
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design process on day one. To excite the students, the ABC documentary of the product design
company, IDEO, will be shown. During the eight minute video, students will learn how the
design process actually works, as the design team must completely redesign the consumer
shopping cart.
The rest of day one will be spent with teams
creating their water filtration systems. Students should
follow the design process in creating a water filtration
prototype. Testing can be conducted using simple water
quality test strips for quick student feedback.
Day 2: Dual Team Pairing and Water Filter
Improvement/Redesign (1:15)
The pivotal part of this lab activity comes during
Figure 1: Steps of the engineering design
second day as teams will be paired together (two teams
process.
per group). Students will then discuss their respective
filtration design and possible improvements; additionally,
teams will discuss possible ways to integrate the two
filtration systems together (thereby improving filtering effectiveness). Testing will then be done
on the effectiveness of the refined filters and discussed with the class. If time permits, the water
cycle for the municipal water supply can be discussed. Discussing how water gets to the students
faucets at home provides a means of relating science class to real-world experiences.
Standards addressed:
Students:



Know repeated experimentation allows for statistical analyses and unbiased
conclusions.
Evaluate data for precision and accuracy based upon repeated experimentation
Recognize that scientific knowledge is constantly changing as scientists investigate
and share new information.
Language Objective:



Students will discuss, design and build a test a water filter.
Students will debate pros and cons of design as well as redesign the filter and share
scientific knowledge gained from experimentation.
Students will record, discuss, and analyze data to draw conclusions about
effectiveness of design.
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Materials:
Each Container has its own theme.
The first box (1) has an actual brita filter, but not very good means to force water through
container.
The second (2) is designed to have all the materials to make a water softner style filter by
layering different types of rocks and sand.
The third (3) is designed to explore the idea of distilling water to filter it.
Container
1
3
3
1,2
1,2,3
1,2
3
1,2,3
1,2
2
2
2
1,2
1,2
1,2
2,3
2
1,2,
Materials(note this is for 6 groups in a single class)
Material
Quantity Price
Notes
Brita water filters
4
$25.00 Only need 2 for one class, but
container usually comes in 4 pack
Water cups for boiling
2
$5.00
Copper pipe
1
$25.00 Comes in long tube length or a
roll, but this needs to be cut into
smaller lengths( 2 ft) for students
Consumables
Panty Hose
Cut-up T shirt
mesh
aluminum foil
rubber bands
Mesh (or netting)
small Rocks
coarse sand
Fine sand
Plastic bags
duct tape
sponges
alum powder
Activated Carbon
toilet paper rolls
Jumbo Ziploc bags
$50.00
found in spice isle
Found in fish supplies
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Engineering a Water Filter
Name _________________________________
Names of team members: _______________________, ________________________, ________________________
Background:
You and your team have become stranded in Bolivia. You have no cell phones, no money, no
access to bottled water and you have avoided drinking the river water for 6 days hoping to be
rescued. Unfortunately there is no sign of rescue and a human can only live without water for 8 to
14 days depending on the quantity of water lost to sweat, tears, and urine. It is time to use the
supplies you have collected to build a filter to purify the water before you are forced to drink it.
Scientists around the world are being challenged to balance their knowledge of chemical
principles to discover innovative solutions to the issue of global drinking water shortages. It is
important they understand the basic principles involved in water filtration and how human
creativity enters into the solution of the problem. In the following exercise, you will design and test
your own filtration system using some basic principles of chemistry.
Goal:
Students will design and test a water filter.
Safety Note:
Although this activity may produce potable water, it is never allowable to drink (or eat) any
substance in a science laboratory. There is always a chance of contamination or an allergic reaction
which could be very dangerous to some students. Also make sure that you wash your hands with
anti-bacterial soap thoroughly before leaving the classroom.
Part 1: Design:
1.
2.
3.
4.
Identify the Problem
Gather information (research)
Develop alternate solutions (first idea may not be the best)
Your water may contain ammonia nitrogen, copper, nitrate, phosphorous, sediment,
and microorganisms.
a. Which do you feel are most important to remove?
b. Why?
5. Describe how you could remove these parameters from your water.
6. Are there any parameters you feel are not important to remove? Explain.
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7. As a team you need to develop a water purification system/device for this water to
make it safe to drink.
a. Sketch your design.
b. Describe how your design will purify the water by labeling each part of the
design
c. and explain why each step/part is necessary.
Rules to follow while designing your filter:
• You will pre and post-test the water and record the results to verify improved quality
(or lack of improvement).
• You may use some or all of the materials in front of you but you will not get any
additional materials.
• You must supply a detailed, labeled drawing of your filtering device, including
measurements indicating how much of each material was used.
• You may filer the water through your filter as many times as you want within the 5
minute filter period.
• Your group must produce a minimum volume of 100 mL of “purified” water.
• You must design, construct and produce the final purified water in the time I have
given you.
• Design and construction: 20 min
• Drawing of finalized filter: 5 min
• Purification of water: 5 min
• You are to store the purified water in the container you are given to be used for the
postfiltering tests on the following day. Make sure that your container is properly
marked with each team member’s full name.
8. How are you going to test this design to ensure it produces safe drinking water?
Answer after filtering your water:
9. Explain the potential health impacts from drinking your water sample.
10. Do you think this water is safe to drink? Explain your answer.
11. Do you think your sample is tap-water or surface water (lake, creek, river,
etc.)? How can you tell?
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Part 2: Testing
Color
Test
Smell
Nitrate
Phosphate
(ppm)
(ppm)
pH
Conductivity
Turbidity
(10 secs)
Before
Filtering
After
Filtering
After
Redesign
Volume Collected after 5 Mins_________mls
Part 3: Re-design
1. Partner with another group to develop a new filter based on both groups design.
2. List the pros and cons for each groups first attempt at the water filter.
3. Brainstorm a new water filter based on the answer to the previous question. Sketch
the new design.
4. What are the differences of this filter from the old filters?
Part 4: Re-Test
Design 1: Draw your initial design for your water filler below. You must:



sketch your design before building
label each part of the design with the material used
explain what you expect each step to do or why it is necessary
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Design 2: Draw your changes to design 1 as you build your filter . You must:




sketch your design before building
label each part of the design with the material used
explain what you expect each step to do or why it is necessary
include measurements
Design 3: Draw your new design as you build your filter with another group. You must:




sketch your design before building
label each part of the design with the material used
explain what you expect each step to do or why it is necessary
include measurements
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