Day #4 Substances in Water Day
Agenda for the Day ............................................................................................................................................... 2
Upper Anchor for Substances in Water ........................................................................................................ 3
Learning Progression Levels for Substances in Solution....................................................................... 4
Substances in Water Activity Sequence ....................................................................................................... 6
Student Learning and Instructional Activity Table: Substances in Water ...................................... 7
Substances Activities ........................................................................................................................................... 8
What’s in the Clark Fork/Santa Cruz River Water and Where Could That Stuff Go? .......... 10
What’s the Difference Between a Solution and a Suspension? .................................................... 13
What Pathways Does Stuff in Solution and Suspension Follow? ................................................ 18
Evaporation with a solar still ............................................................................................................... 21
Surface Water Runoff .............................................................................................................................. 22
Celery Stalk ................................................................................................................................................. 23
Soil column .................................................................................................................................................. 24
So What Could Be Coming Down Our River and Where Could it End Up? .............................. 27
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Day #4 Substances in Water Day
Agenda for the Day
8:30
Leave for Milltown Overlook
9:00
Milltown Overlook
10:30 Substances Upper Anchor & LP
11:00 Formative Assessments for Substances
Fertilizer assessment
Construction assessment
12:00 Lunch
12:45 Substances Tools
Tracing Mixtures in Water
Scale Tool
1:15
Substances Activity Sequence & Tools for Reasoning
What is in the water?
Solutions & Suspensions
Tracing Substances
Solar Stills
Celery
Soil Column
Enviroscape
3:00
Break
3:15
School Year Activities
4:00
Wrap-up and closing
4:30
Evaluations
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Upper Anchor for Substances in Water
Structure & Systems and Scale: Naturally occurring water on the Earth is a mixture of water
and other substances. Two types of mixtures are solutions and suspensions. These mixtures are
best described at the atomic-molecular and microscopic scales.
 Solutions (Atomic-Molecular Scale): Solutions are homogeneous mixtures. As such, they
have a constant composition of constituents regardless of the section or zone of the
mixture observed. A solute is dissolved in another substance, the solvent. Particles are
not visible in the water, although changes in color and other properties may occur.
Substances that dissolve in water are composed of polar molecules that are pulled apart
into their component ions or are stabilized as a whole by the electrostatic forces of the
polar water molecules.
 Suspensions (Microscopic Scale): Suspensions are heterogeneous mixtures that have
different composition across the section of the mixture observed. Particles in
suspension are visible (macroscopic to microscopic) in the water. Substances in
suspension include organic and inorganic materials.
Processes & Scientific Principles:
 Solutions: Solutions move mix and move with water through surface, groundwater, and
biotic systems. Substances can also mix with water in the atmospheric system, but do
not move from the surface to atmospheric system with water. Substances that dissolve
in water are usually polar molecules. The polar nature of the water molecule pulls apart
substances that have weaker ionic bonds, such as salt. How much of a substance can
dissolve in water depends on the solubility of the substance in a given temperature of
water and how much of the substance is already dissolved in the water (saturation).
Dissolved substances separate from water when the constituent parts recombine or
combine with other substances to make new substances that are not soluble in water,
when water changes state and reduces the ratio solvent/solute, and when water
changes temperature affecting the solubility of the solute.
 Suspensions: Suspensions mix and move with water through the surface water system.
How much substance moves in suspension depends on the kinetic energy of the moving
water. Faster water can move more suspended material than slower water. Particles in
suspension will settle out of the water due to gravity. Smaller substances will settle out
more slowly than larger particles. Particles in suspension can be filtered or centrifuged
from the water.
Representations: Substances in solution are represented by descriptions, drawings, or
notations at the atomic-molecular scale. Molecular diagrams that show relative sizes and
charges of atoms are necessary. Substances in suspension are represented at the microscopic
scale with descriptions or drawings showing relative sizes of particles.
Dependency & Human Agency: The replenishing of high quality freshwater supplies depends
on well-functioning natural ecosystems to filter substances in suspension and dilute substances
in solution. Human actions can adversely affect the function of ecosystems or reduce the size of
these ecosystems, thus reducing the capacity of these systems to provide fresh water. Human
actions can also introduce substances that mix in both suspension and solution. While natural
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processes can remove these substances, their capacity to do so is limited by evaporation and
infiltration rates. Concentrations of substances in water can be diluted but is limited by the
volume of water available and necessary for dilution.
Learning Progression Levels for Substances in Solution
Level 4: Model-Based Accounts
Structure & Systems: Level 4 accounts identify the chemical nature of substances in water and
describe changes in water quality at the atomic-molecular scale. They distinguish between
substances in solution and suspension.
Scale & Representations: Drawings show substances in solution and suspension at the atomicmolecular scale and often indicate awareness of the polar nature of the water molecule and its
role in dissolving substances. Uses representations as models.
Scientific Principles: Level 4 accounts explain why substances in solution do not move with
water from the surface to atmospheric system.
Dependency & Human Agency: Identifies limitations of environmental systems to provide fresh
water.
Level 3: School Science Accounts
Structures & Systems: Level 3 accounts relate water quality to the type of substances mixed
with water. Level 3 accounts categorize types of substances that can be in water with moderate
specificity, such as referring to “fertilizers” or “pesticides,” but do not identify the chemicals or
elements in these substances. Level 3 accounts distinguish between biotic materials, such as
bacteria, and non-biotic substances, such as silt, sand, and salt. Level 3 accounts distinguish
suspensions from solutions based on whether or not substances can settle out, but often refer
to anything microscopic, such as bacteria, as being in solution.
Scale & Representations: Recognizes that there may be substances mixed in water may be
smaller than can be visibly seen, but do not distinguish between microscopic and atomicmolecular scales. Thus, these accounts may talk about molecules or atoms but only as particles
that cannot be seen.
Scientific Principles: Traces substances mixed with water but does not apply model-based
drivers or constraints. As a result, descriptions of pathways may be incomplete or implausible.
For example, level 3 accounts may not recognize the role of water in the transportation of
substances moving through underground systems or may trace water into the atmosphere with
water.
Dependency & Human Agency: Includes humans systems as part of the environmental systems
through with substances in water move, but does not recognize in principled ways the
limitations of environmental systems to provide fresh water.
Level 2: Force-Dynamic Accounts with Mechanisms
Structures & Systems: Level 2 accounts relate the quality of water to whether or not there is
visible (e.g., trash), tasteable (e.g., salt) or generally “bad” substances (e.g., bad chemicals) in
the water. Level 2 accounts provide generic labels for substances, such as “chemicals.”
Changing the quality of water requires actors to remove “bad” substances or add “good”
substances (e.g. chemicals to purify water). Level 2 drawings of suspensions and solutions do
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not distinguish between types of mixtures. Level 2 accounts indicate that systems are
connected, but they often do not indicate that water and substances in water do not always
follow the same pathways.
Scale & Representations: Broad macroscopic, but does not trace substances long distances or
describe molecular or atomic-molecular scale. When describing what is in the water, level 2
accounts often describe visible objects such as trash or generic substances such as “pollution.”
Drawings of substances in water show macroscopic-scale representations of substances in
water.
Scientific Principles: Accounts use force-dynamic mechanisms to change “bad water” into “good
water.” Often, someone or something is required to remove the “bad stuff” or add the “good
stuff” to water to make it clean or drinkable. These accounts also frequently rely on special
circumstances to explain changes in water quality.
Dependency & Human Agency: Humans benefit from and are impacted by changes in water
quality. Humans can also cause changes in water quality.
Level 1: Force-Dynamic Accounts
Structures & Systems: Level 1 accounts of substances in water describe different qualities of
water as different types of water. For example, students may describe water as dirty, clean,
fresh, salty, polluted, lake, bathtub, drinking, etc. These terms all refer to different kinds of
water that are separate and distinct from each other.
Scale: These accounts are limited to the macroscopic and immediate scale.
Scientific Principles: Level 1 accounts suggest that different types of water can be changed into
other types of water by being purified or cleaned, usually by a person or a human-created
agent such as a “human water cleaning system.”
Representations: No connections are made between representations and the physical world.
Dependency & Human Agency: Accounts state that people need clean water. Water serves to
fulfill the needs of humans.
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Substances in Water Activity Sequence
Activity/Description
Suspensions &
Solutions
Students explore the
difference between
solutions and
suspensions
Tracing Pathways
Learning Goals – Practices fused
with content
- Investigate and analyze and
interpret data about
properties of mixtures
- Engage in arguments from
evidence about types of
mixtures
Formative
Scientific Principles
Assessments
- Fertilizer
- Type of mixture
(solutions)
- Conservation of
- Construction
matter
Site
(suspensions)
Representations
Tools
Physical models
- Scale Tool
-
- Fertilizer
- Type of mixture
(solutions)
- Conservation of
- Construction
matter
Site
(suspensions)
- Water inside
plant
(Transpiratio
n)
- Physical
models
- Molecular
models
- Tracing Mixtures
Tool
- Scale Tool
- Fertilizer
- Drivers &
(solutions)
Constraints for
water
- Construction
Site
- Type of mixture
(suspensions)
Maps
Cross-Sections
- Pathways Tool
- Drivers and
Constraints Tools
- Tracing Mixtures
Tool
Students explore how
substances in water
move through various systems
-
Substances in the
Watershed
Students trace
substances through a
watershed
-
-
Use models to traces
substances in water through
systems
Investigate and analyze and
interpret data about
movements of substances in
water
Construct explanations about
movements of substances in
water.
Engage in arguments from
evidence about pathways of
substances in water in a
watershed.
Construct explanations about
pathways of substances in
water in a watershed.
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Student Learning and Instructional Activity Table: Substances in Water
What students need to work on
(Foci for instruction)
Structure &
Systems:
Scale
Scientific
Principles
Representatio
ns
Substances mix with water as either
suspensions or solutions. L2 to L3
Solutions &
Suspensions
Tracing Substances
through Systems
Substances in the
Watershed
Investigate how and why
substances in suspension
and solution move
through various systems
L2 to L3 to L4
Explain and predict
pathways of substances
in suspension and
solution through various
systems L2 to L3 to L4
Use scale tool to
describe sizes of particles
in suspension and
molecules in solution
L2 to L3 to L4
Use scale tool to
describe sizes of particles
in suspension and
molecules in solution
L2 to L3 to L4
Explore how and why
substances in suspension
and solution move along
with water through
various systems L2 to L3
to L4
Investigate how and why
substances in suspension
and solution move
through various systems
L2 to L3 to L4
Explain and predict
pathways of substances
in suspension and
solution through various
systems L2 to L3 to L4
Describe/represent
relative sizes of particles
in suspension and
molecules in solution
L2 to L3 to L4
Describe/represent
relative sizes of particles
in suspension and
molecules in solution
L2 to L3 to L4
Describe/represent
relative sizes of particles
in suspension and
molecules in solution
L2 to L3 to L4
Traces substances
through connected
systems L2 to L3 to L4
Explain and predict the
effects of substances
mixing with water L2 to
L3 to L4
Investigate properties of
substances L2 to L3 to L4
The nature of the mixture depends on
the chemical properties of the substance
that mixes with water. L3-L4
Macroscopic to microscopic L2-L3
Use scale tool to describe
Microscopic to atomic-molecular L3 to
sizes of particles in
L4
suspension and molecules
in solution
L2 to L3 to L4
Substances in water do not always
follow the same pathways as water. L2
to L3
The pathways substances follow
depends on the nature of the mixture
(suspension or solution) L3 to L4.
Representations at microscopic scale L2
to L3
Representations at atomic-molecular
scale L3 to L4
Humans can change water quality L2 to
L3
Dependency &
Human Agency Recognizes limitations of environmental
systems to provide fresh water. L3 to L4
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Substances Activities
Summary of Activities
Activity #1: What’s in the Clark Fork/Santa Cruz River Water and Where Could That Stuff Go?
Students indicate their ideas (through drawing and labeling) about what could be in river water
and where stuff in river water could go.
Activity #2: What’s the Difference Between a Solution and a Suspension?
Students compare and contrast food coloring in water, salt in water and dirt in water. They
make observations about size of particles, distribution of substance in water, whether or not
the mixture settles, whether or not the substance can be separated from water with a filter,
and whether or not particles in the mixture scatter light. After making and recording
observations, students learn the definitions of solution and suspension.
Activity #3: What Paths Does Stuff in Solution and Suspension Follow?
Through using physical models that replicate what happens in environmental systems such as
the Clark Fork River corridor and the Santa Cruz River corridor, students investigate how
substances in solution and suspension separate or stay with water as they move through
different systems.
Activity #4: So What Could Be Coming Down Our River and Where Could it End Up?
Students apply their investigations in Activity 3 to consider where substances in solution and
suspension might go to.
Activity #5: A Grave Mistake (Project Wet)
Students analyze data to trace the flow of contaminants in groundwater and consider
consequences for communities.
Learning Goals
In these activities, students explore the following questions.
1. What’s in river water and where could that stuff go?
2. What’s the difference between a solution and a suspension?
3. How do substances in solution mix with, move with, and separate from water in
environmental systems?
4. How do substances in suspension mix with, move with, and separate from water in
environmental systems?
Content Fused with Practices
1. Investigate, analyze and interpret data about properties of mixtures and pathways of
substances through systems.
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2. Engage in arguments from evidence about pathways of substances in water through
systems.
3. Use models to traces substances in water through systems
4. Construct explanations about pathways of substances in water in a watershed.
Cross-Cutting Themes
1. Patterns in characteristics of suspensions and solutions
2. Differences in scale of materials in solution and suspension
3. Pathways of other substances mixed with water through hydrologic systems
4. Changes in distribution of both human-introduced and natural substances in
environmental systems
Formative Assessments
1. Use the Fertilizer assessment to develop understanding of students’ ideas about what
type of mixture fertilizer forms with water and where that type of mixture can go in
connected hydrologic systems.
2. Use the Construction Site assessment to develop understanding of students’ ideas
about what type of mixture soil forms with water and where that type of mixture can go
in connected hydrologic systems.
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What’s in the Clark Fork/Santa Cruz River Water and Where Could That Stuff Go?
Summary of Activity
Students indicate their ideas (through drawing and labeling) about what could be in river water
and where stuff in river water could go.
Materials
 “What’s in the Clark Fork/Santa Cruz River Water and Where Could That Stuff Go?”
handout
Time
About 30 minutes
Question: Establish a question and elicit student ideas
1. Ask students to complete the “What’s in the Clark Fork/Santa Cruz River Water and Where
Could that Stuff Go?” sheet. This activity will give you an opportunity to elicit student ideas.
2. You may want to administer this the day before you complete the other activities so that
you’ll have an opportunity to review students’ ideas about watersheds.
3. Optional: Have students share out their ideas about what a watershed is. You may choose
to use a document projector so students can share their drawings and ideas about what is
in the river water.
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What’s in the Clark Fork River Water and Where Could That Stuff Go?
Here is a cross-section of the Clark Fork River near Milltown. What do you think could be in the Clark Fork
River water near Milltown? In the picture below, draw and label what you think could be in the water.
Choose three things you labeled in your drawing and describe where you think each thing could go next.
Stuff/thing in the river water
Where could it go from the river water near Milltown?
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What’s in the Santa Cruz River Water and Where Could That Stuff Go?
Here is a cross-section of the Santa Cruz River in Tucson after it rains. What do you think could be in the Santa
Cruz River in Tucson In the picture below, draw and label what you think could be in the water.
Choose three things you labeled in your drawing and describe where you think each could go next.
Stuff/thing in the river water
Where could it go from the river water in Tucson?
12
What’s the Difference Between a Solution and a Suspension?
Summary of Activity
Students compare and contrast food coloring in water, salt in water and dirt in water. They
make observations about size of particles, distribution of substance in water, whether or not
the mixture settles, whether or not the substance can be separated from water with a filter,
and whether or not particles in the mixture scatter light. After making and recording
observations, students learn the definitions of solution and suspension.
Materials:
For demo plus for each group
 3 glasses or beakers
 3 cups of water
 1 tsp salt
 1 tsp food coloring
 1 tsp dirt
 1 Spoon
 3 pieces of filter paper or filter cones
 Laser pointer (use with care for eye safety and can be shared among groups)
 Suspensions and Solutions Chart
For each student
 Science notebook
 One observation/test table handout
Time:
Two class periods
Explore Phenomena for Patterns
1. Begin by providing a demonstration. Take three glasses, each with 1 cup of water. To the
first glass, add 1 teaspoon of salt. To the second glass, add 1 teaspoon of food coloring, to
the third glass, add 1 teaspoon of dirt. Ask the students to observe the three mixtures, draw
a picture of each, and label characteristics of each. Make a column for each
Practices
mixture on the board and ask students to share out their ideas about
Carry out
characteristics of each mixture.
investigations
2.
Next, assign students to groups of four or five. Each group should
Analyze &
receive materials to reproduce the mixtures described above. Let students
interpret data
know that they will be conducting several short experiments to more
closely examine some similarities and differences between the three
mixtures. Students can either use their science notebook or the table below to record their
predictions and observations. This investigation will take two days. For each mixture,
students will:
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a. Make observations about size of particles of substance in water (visible or not
visible)
b. Make observations of distribution of substance in water (evenly or unevenly
distributed)
c. Predict, then test whether or not the substance settles out of the water
d. Predict, then test whether or not the substance can be separated from water with a
filter.
e. Test whether or not particles in the mixture scatter light.
3. After students have completed observing, testing and recording, provide each group with a
solutions and suspensions chart. Groups should use their observations and this chart to
decide what type of mixture each sample is.
4.
Students in their groups should also use the scale tool to identify
Practices
the scale of size of the particles in the different mixtures.
Construct
5.
Ask groups to share their conclusions and the evidence they used
explanations
to make their conclusions. Students can agree or disagree with each
Make
other about the classifications. Facilitate the students in coming to
arguments
consensus that the salt and food coloring mixtures are solutions and that
from evidence
the dirt mixture is a suspension.
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Examine the three mixtures further by observing, testing, and recording what you find in this table.
Salt in water observations
Food coloring in water
observations
Day One
How large are the particles that
are mixed in water (for example,
are they large enough to see)?
Is the substance mixed evenly or
unevenly with the water?
Describe.
Using the laser pointer, test
whether or not light is scattered
(you can see the colored light
beam in the water) by the
mixture?
Predict whether or not you think
the substance will settle out of the
water if it is left standing
overnight. Describe why.
Predict whether or not you think
the substance can be filtered out
of water when poured over filter
paper? Describe why.
Day Two
After standing undisturbed
overnight, did the substance settle
out of the water?
(If the mixture settled, stir it again
before doing this test). Was the
substance filtered out of water
when poured over filter paper?
Conclusion: What type of mixture
is this?
Dirt in water observations
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Comparison of Solutions and Suspensions
Characteristics
Solution
Suspension
Size of particles mixed with water
Particles are less <1 nanometer in size (too
small to be seen with eye)
Particles can be seen with naked eye (larger
than 100nm)
Separation by filtration
Particles will pass through a paper filter; cannot be
separated except through distillation
Can easily be separated by filtering
Settles
Particles do not settle when mixture is left
undisturbed.
Particles settle out of water when mixture is
left undisturbed.
Scatters light
No (cannot see colored light beam passing
through mixture)
Yes (can see colored light beam passing
through mixture)
16
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What Pathways Does Stuff in Solution and Suspension Follow?
Summary of Activity
Through using physical models that replicate what happens in environmental systems such as
the Clark Fork River corridor and the Santa Cruz River corridor, students investigate how
substances in solution and suspension separate or stay with water as they move through
different systems.
Materials
 Substances Pathways Table for each student
 Materials listed for each experiment
 Tracing Mixtures Tools for each student
Time
About two class periods of time if done as a jigsaw activity (different groups do different tests).
However, some of the experiments require more than one day of observations. Plan
accordingly.
Establish a Question and Elicit Students’ Initial Ideas
1. Tell students that they will now explore how several substances could move in water
through our river system. They will consider nitrates, which can enter the river from
sources including agricultural use of fertilizers and from cattle and other animal wastes.
When nitrates mix with water they dissolve and form a solution. In this activity, nitrates
will be represented with green food coloring in water. They will also consider arsenic,
which can enter the river from mining wastes. Arsenic can be found in river water in
both dissolved form (solution) and in a form that is attached to sediments (suspension).
Dissolved arsenic will be represented with red food coloring. Arsenic attached to
sediment particles will be represented with red sand.
2. Ask the students to make predictions about where these substances can go from the
river water on the Substances Pathways Table.
3. Next, place students in groups of about four students. Each group will
Practices
test one or more of the following pathways with both a solution (food
Carry out
coloring in water) and a suspension (red sand mixed in water). Note that
investigations
students only need to test one substance in solution --- they can then
Analyze &
extrapolate results for how most solutions move through connected
interpret data
systems. The instructions for the different tests are provided in the pages
below the table.
a. Can the substance move with water into the atmosphere
(solar still)?
b. Can the substance move with water further down the river (enviroscape or other
watershed model)?
c. Can the substance move with water through the groundwater (soil column)?
d. Can the substance move with water into plants (celery stalk)?
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4. After students conduct their tests, create a class chart showing all of the results. Did the
test results match students’ predictions? If multiple groups conducted the
Practices
same tests, did they get the same results?
5. Students in their groups can next choose a substance and a place
Construct
explanations
that they tested and complete a Tracing Mixtures Tool. After groups
complete their tools, have them share their completed tools with the
Make
class and discuss their results and ideas about why the substance in the
arguments
mixture either stayed with water or separated from water on the
from evidence
pathway.
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Substances Pathways Table
Will this mixture move with
water into the
atmosphere?
Prediction
Observation
Will this mixture move with
water further down the
river?
Prediction
Observation
Will this mixture move with Will this mixture move with
water through the
water into plants?
groundwater?
Prediction
Observation Prediction
Observation
Nitrates in
solution
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Arsenic in
solution
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Arsenic in
suspension
(attached to
sediments)
Choose three of your predictions above and explain why you made the prediction you did for each.
1.
2.
3.
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Evaporation with a solar still
Driving Question: What happens to substances in water when the water evaporates into the air?
Materials
 1 – large container
 1 – small container
 1 small stone – (cold – place in freezer)
 Plastic wrap
 Conductivity meter (optional)
 1 Teaspoon
 Tape
 Substance mixed with water
1. Students can build their solar stills as shown above. They should place their mixture
(e.g., 1 cup of water with three drops of food coloring) into the bottom of the large
bowl. Next, place a smaller, empty glass cup in the center of the large bowl. Place plastic
wrap over the top of the large bowl and seal. Then place a rock in the middle of the
plastic wrap. The rock will direct the condensate back into the glass cup in the middle of
the bow (should produce a little slope along the plastic toward the inner cup). This test
takes more than one class period. Solar stills need to be placed in strong sunlight or
under a strong artificial light that gives off heat to work. Distilling a sufficient sample of
water may take several days so consider setting this test up earlier if you would like to
conduct this lesson in just one or two class periods.
2. After the solar still has had time to work, students can carefully remove the plastic wrap
and remove the inner cup from the bowl. Have students compare the mixture in the
large bowl with the mixture in the cup. How did the water get into the small cup? Did
the substance move with the water into the small cup. Students can make visual
observations of the differences. They can also use a conductivity meter to test whether
there are dissolved substances in both of the containers.
3. Students should now record their observations --- did the substance stay mixed with the
water when moving into the atmosphere, or did it separate? If it separated, how/why
did it separate? Could polluted water make polluted rain? Does salty water make salty
rain? Why or why not? What is your evidence?
Students should find that none of the substances evaporate and condensate with the water.
Water is a mixture of substances and the substances and water do not change phase at the
same time or under the same conditions. Substances in suspension do not change phase and
are too large to move with water molecules into the atmosphere. Substances in suspension will
precipitate out of solution.
******************************************************************
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Volatility of non-water substances
Extension activity for advanced high school courses
Some substances will vaporize separately from water and then recombine either in the
atmosphere or just return to the ground on their own. If you want to show this you can make a
solar still with orange juice in it – the water in the cup should taste/smell like citrus though the
color will most likely not transfer.
Surface Water Runoff
Driving Question: Which substances are transported with water in surface runoff?
Materials:
Watershed model (We used this one in a paint tray
liner) OR
Enviroscape
Substance being investigated (drop of food coloring
or colored sand)
Tablespoon
Bucket for water disposal
Watering can
1. Have each group place a tablespoon of their substance at the top of the paint tray.
2. Mist it with water using the spray bottle and record you observations in the lab sheet.
3. Pour water from a watering can over your substance and record you observations in the
lab sheet. Which substances will travel with surface flow? Does the velocity of the
water matter?
Students will notice that all substances mixed with water (in either suspension or solution) will
runoff with water in the surface system. However, larger and heavier particles in suspension
may settle out before smaller particles and substances in solution.
22
Celery Stalk
Driving Question: Which substances move with water into plants?
Labeled beakers with mixtures students are investigating (one solution
and one suspension)
2 celery stalks with leaves
1. Add a celery stalk to each beaker.
2. Seal a plastic bag over the top of the celery stalk.
3. Place the beakers in a sunny location.
4. Over the course of a week, record observations in a science notebook.
5. Compare results among groups. Allow students to share their ideas and reasoning before
providing scientific explanations.
Students will find that the substances in solution will travel up into the celery but the
substances in suspension will not. None of the substances change phase with the water when it
transpires.
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Soil column
Driving Question: Which substances move with water into the soil and through the
groundwater?
Materials for each group:
1 clear plastic water bottle
1 mesh screen squares (10 cm x 10 cm)
1 rubber band
Scissors
Conductivity meter (optional)
Media (ex. sand, rocks, and/or soil)
Tape & Sharpie Marker
Substance mixed with water
1. Remove bottle cap and labels from plastic water bottles. Label the bottle with your group
name and substance. Fasten the mesh screen tightly over the mouth of each bottle using a
rubber band. Carefully cut the bottle in half as shown in the diagram. Turn the top half
bottle upside down and place in the bottom half of the bottle. Fill the inverted bottle top
half way with media.
2. Stir each mixture, and slowly pour it into the soil column. Allow all of the surface water to
drain through the soil column into the bottom half of the bottle.
3. Measure the conductivity of the water in the bottom half of the bottle.
4. Record you observations. Which substances will travel with water into the ground?
Students should find that the soil filters out the substances in suspension but not the
substances in solution.
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So What Could Be Coming Down Our River and Where Could it End Up?
Summary of Activity
Students apply their investigations in Activity 3 to consider where substances in solution and
suspension might go.
Materials
Application questions
Time
One class period or longer if students investigate what is and/or could be done about
substances in river water.
Application
Engage students in considering and providing explanatory accounts of the following questions.
Students can work in small groups and then share ideas with the whole class.
Missoula
In Missoula, could the following substances from each of the sources identified (arsenic in
sediments, arsenic in solution, nitrates in solution)…
1. Get into our drinking water that is supplied from wells near the Clark Fork River?
2. Get into the atmosphere and cause problems as air pollution?
3. Runoff and end up further down the river (e.g., near Frenchtown or behind the Noxon
Rapids Dam or in the Columbia River or in the Pacific Ocean)? Could it run off and end
up in the Bitterroot River or the Flathead River?
4. Get into any crops or plants that we grow near the river with river surface water
irrigation?
Which possible outcomes would we need to plan for and what do you think we could/should do
to protect our Clark Fork Water Resource?
Tucson
In the Santa Cruz River watershed, upstream from Tucson, are several large copper mines with
tailings piles. These tailings piles are made of a slurry (wet mud) of mine waste high in arsenic
and heavy metals. Where might the arsenic go?
1. Could it get into the aquifer near the tailings piles? How?
2. Could it get into the air? How?
3. Could it get into the Santa Cruz River water when it rains? How?
Also in this area are agricultural areas which use nitrate fertilizer. Where could the nitrates go?
1. Could it get into the aquifer near the tailings piles? How?
2. Could it get into the air? How?
3. Could it get into the Santa Cruz River water when it rains? How?
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