Welcome 
For the next 45-55 minutes we are asking you
to engage in the activity as a learner. After the
lesson we will look at the lesson through your
eyes - the eyes of a teacher.
Open up your science notebook…
 Begin a new entry,
possible title: “Concentration and Osmosis”
 Include today’s date.
 Record the focus question for today’s lesson.
Focus Question:
How is the concentration of a solution related
to its effects on other substances?
Respond to the following…
 Drinking water in our homes contains low
concentrations of dissolved chlorine, a highly
toxic substance. Why is it safe to drink the
water?
 What do you think ‘concentration’ means?
Where have you seen this term before?
When you are done writing, turn to a neighbor and share your
thinking. Feel free to write down additional information.
Now take a look at this…
tp://www.youtube.com/watch?v=H6N1IiJTmnc
Record your observations in your science
notebook.
Then explain why this video is called “osmosis in
the kitchen”. What is osmosis? Where have you
heard this term before?
When you are done writing, turn to a neighbor and share your
thinking. Feel free to write down additional information.
Consider this…
More than 36 million people in North America use
contact solution to store their contacts. Most
contact lenses solutions contain some saline
solution (water that contains dissolved salts.)
 One purpose of the saline solution is to keep the water
balance of the lenses correct. Why do you think this
‘water balance’ is important? What would you
recommend to someone that did not have any contact
solution to store their contacts in overnight?
When you are done writing, turn to a neighbor and share your thinking. Feel free
to write down additional information.
Today we will explore
some of these
questions by
examining gummi
bears…
History of Gummi Bears
• The gummi bear originated in Germany
• Haribo company 1922, the Dancing Bear, a fruitflavored gum made in the shape of a bear - later
become Haribo's world-famous Gold-Bears candy
product in 1967.
• Trolli (another gummi candy manufacturer) first
introduced gummi worms in 1981.
• Gummi bears are also one of the few types of
candy to have been turned into a television show.
Gummi Bears - Typical Ingredients
•sugar
•glucose syrup
•starch
•flavoring
•food coloring
•citric acid
•gelatin
Gummi Bears Gummy Bears
• 1 gummy bear in each cup
• Soaked overnight in… (2-3 hr minimum)
– water
– 0.1 M salt soln, 0.5 M salt soln, 1.0 M salt soln
– 0.1 M sugar soln, 1.0 M sugar soln, 2.0 M sugar soln
– corn syrup
– air
• What do you think will happen? Record your
thoughts in your science notebook. Be specific.
Background Information
A solution is a mixture of two or more
substances that is uniform throughout.
The substance that is present in the greatest
amount is called the solvent, the solute is
dissolved in the solvent.
Background Information
Concentration is the amount of solute present in a
mixture or solution for a specified amount of
solvent.
A common measure of concentration is moles per L,
moles/L, which is referred to as molarity, M.
When a substance is diluted it means it is less
concentrated.
Gummi Bears Gummy Bears
In your science notebook, record your scientific*
observations of the gummy bears.
* thorough
* accurate
* qualitative
* quantitative
*
*
When you are done, rank the gummy bears
according to size from smallest to largest.
Record your ranking.
Gummi Bears Gummy Bears
When you are finished making observations, please
clean up !
• Remove gummy bears from solutions, place them in
a paper towel and place the towel in the trash.
• Pour the solutions down sink, rinse the cups and
spoons with water, and dry them all before returning
them to the ziplock bag provided.
– If you mix some water with the corn syrup, it will come
out of the cup easier.
Discuss these questions with your group
and record your best thinking:
1. What does it mean when a scientist says that a 1.0
M solution is more concentrated than a 0.1 M
solution?
2. How does the size of the gummy bear relate to the
concentration of the solution it is in?
3. How do the sizes of the gummy bears in the sugar
solutions compare with those in the salt solutions?
4. What is happening – at the particle* level – to
explain your observations? Be sure to include a
diagram that shows the movement of particles into
or out of the bears.
(*particles refer to molecules and ions)
You may want to refer to the word wall to incorporate some scientific vocabulary
into your explanations.
Word Wall
•
•
•
•
•
Observations
Qualitative
Quantitative
Claim
Evidence
•
•
•
•
•
•
•
Solution
Solute
Solvent
Particles
Concentration
Molarity
Diluted
• Diffusion
• Osmosis
• Selectively
permeable
• Passive
transport
• Active
transport
Discuss one or more of these questions with the
class. Be sure to record any changes in your
thinking because of the class discussion.
1. What does it mean when a scientist says that a 1.0 M solution is
more concentrated than a 0.1 M solution?
2. How does the size of the gummy bear relate to the concentration of
the solution it is in?
3. How do the sizes of the gummy bears in the sugar solutions compare
with those in the salt solutions?
4. What is happening – at the particle* level – to explain your
observations? Be sure to include a diagram that shows the
movement of particles into or out of the bears.
(*particles refers to molecules and ions)
Read the handout provided by your teacher.
Compare the information in the handout to your
best thinking about the questions below. Be sure
to record any changes in your thinking because
of what you read.
1. How does the size of the gummy bear relate
to the concentration of the solution it is in?
2. How do the sizes of the gummy bears in the
sugar solutions compare with those in the
salt solutions?
3. What is happening – at the particle* level – to
explain your observations?
(*particles refers to molecules and ions)
Handout: Explaining the Gummy Bear Observations
In the gummy bears, the sugar could not move into and out of the bears easily – probably
because of the presence of the gel. Instead, it is the water moving from an area of high
concentration – of water – to an area of lower concentration – of water. The gummy bears
plumped up the most when they were placed in water. This is because the concentration of water
outside the bear was much higher than the concentration of the water inside the bear. The water
will continue to move until the concentrations of substances inside and outside of the bear are
the same. When the bears were placed in a solution with a high concentration of sugar, the bears
only plumped up a little. When the bears were placed in a solution with a concentration of sugar
higher than that of the bear, the bear became smaller. In the case of the corn syrup, the
concentration of water inside the bear was actually higher than the concentration of water
outside of the bear at the beginning of the experiment.
Dots represent sugar molecules. Arrows show the direction of water movement.
Handout: Osmosis / Diffusion
• Osmosis is the movement of water across a selectively permeable
membrane from an area of high water potential (low solute concentration)
to an area of low water potential (high solute concentration).
• Osmosis is a passive process, like diffusion which describes the spread of
particles through random motion from regions of higher concentration to
regions of lower concentration.
• Net movement of solvent is from the less-concentrated (hypotonic) to the
more-concentrated (hypertonic) solution, which tends to reduce the
difference in concentrations.
• The osmotic pressure is defined to be the pressure required to maintain an
equilibrium, with no net movement of solvent. Osmotic pressure is a
colligative property, meaning that the osmotic pressure depends on the
molar concentration of the solute but not on its identity.
Take a look back…
Consider the opening questions to this lesson…
 chlorine in drinking water
 improving wilted lettuce or contact solution
What have you learned today that would change
your response to the question(s)? Record these
thoughts.
Exit Ticket –
Today’s purpose: Explain how the concentration of a solution
is related to its effects on other substances?
Write your response to the question below on an index card. Be sure to put
your name, date and period on the card. Turn the card in to your teacher
before you leave class.
What would happen if you placed a gummy bear in
a 1.5 M sugar solution overnight?
 Use your data to help determine the outcome.
 Draw a picture showing which way the
molecules are moving.
 Explain your answer in terms of the diffusion of
water in or out of the bear.
The lesson is completed at this point.
Now we are going to ask you to consider the
lesson as a teacher.
Discussion question 1:
How does the lesson you just participated in
support the new Colorado Science Standards?
 Work with 1 or 2 other people to highlight
where you see this lesson aligning with the
standards. Be sure to consider both the left
and the right side of the standards page(s).
•
handout of HS and MS standards provided
 Record and discuss your findings.
Colorado Science Standards
Science
Grade Level Expectations at a Glance
Standard Grade Level Expectation
High School
2. Life Science
3. Cellular metabolic activities are carried out by biomolecules produced by
organisms.
4. The energy for life primarily derives from the interrelated processes of
photosynthesis and cellular respiration. Photosynthesis transforms the sun’s
light energy into the chemical energy of molecular bonds. Cellular respiration
allows cells to utilize chemical energy when these
bonds are broken.
5. Cells use the passive and active transport of substances across membranes to
maintain relatively stable intracellular environments.
6. Cells, tissues, organs, and organ systems maintain relatively stable internal
environments, even in the face of changing external environments.
Content Area: Science Standard: 2. Life Science
Prepared Graduates:
• Analyze the relationship between structure and function in living systems at a
variety of organizational levels, and recognize living systems’ dependence on
natural selection
Grade Level Expectation: High School
Concepts and skills students master:
5. Cells use passive and active transport of substances across membranes to
maintain relatively stable intracellular environments
Evidence Outcomes Students can:
a. Analyze and interpret data to determine the energy requirements and/or
rates of substance transport across cell membranes
b. Compare organisms that live in freshwater and marine environments, and
identify the challenges of osmotic regulation for these organisms
c. Diagram the cell membrane schematically, and highlight receptor proteins as
targets of hormones, neurotransmitters, or drugs that serve as active links
between intra and extracellular environments
d. Use tools to gather, view, analyze, and interpret data produced during
scientific investigations that involve passive and active transport
e. Use computer simulations and models to analyze cell transport mechanisms
21st Century Skills and Readiness
Competencies
Inquiry Questions:
1. What variables affect the rate of transport across a membrane?
2. Why is it important that cell membranes are selectively permeable?
Relevance and Application:
1. Osmotically balanced solutions such as intravenous and ophthalmic solutions are critical in
medical settings.
2. Drugs target receptor proteins such as hormones and neurotransmitters in membranes and mimic
the action of natural signals there.
3. Technology is used to support humans on dialysis.
Nature of Science:
1.
Ask testable questions and make a falsifiable hypothesis about how cells transport materials
into and out of the cell and use an inquiry approach to find the answer.
2.
Share experimental data, and respectfully discuss conflicting results emulating the practice of
scientists.
3.
Recognize and describe the ethical traditions of science: value peer review; truthful reporting of
methods and outcomes; making work public; and sharing a lens of professional skepticism when
reviewing the work of others.
Discussion question 2:
How does the lesson you just participated in
support professional expectations as seen in
the new teacher evaluation tool?
 Work with 1 or 2 other people to highlight
where you see this lesson aligning with the
new teacher evaluation tool.
• handout of part of the evaluation tool provided
 Record and discuss your findings.
I. Professional Preparation
Purposeful planning for instruction as evidenced
by:
• Knowledge of current District 11 curriculum
and Unified School Improvement Plan
(USIP) goals
• Knowledge of subject
• Knowledge of research-based best practices
II. Professional Techniques and Strategies
Demonstrates professional techniques that:
• utilize effective teaching strategies that
enhance student learning
• establish a classroom environment
conducive to learning
Time to Reflect
Please take a few minutes to reflect on your
classroom experience today by responding (in
writing – in your notebook) to the questions
below:
• How does the lesson you experienced today
compare to lessons in your current classroom?
(similarities? differences?)
• What aspects of the lesson today would you
like to incorporate into your classroom?
The following series of slides contains
additional information on osmosis / diffusion,
including a few applications as well as related
tutorials and youtube videos.
Additional Info: Osmosis / Diffusion
Osmosis
The tendency for aqueous solutions [solvents] to migrate across a
semi-permeable membrane from a higher water potential to a lower
water potential is known as diffusion. Semi-permeable membranes
are selective, allowing only specific particles to flow through and
preventing others from invading. Water always flows from lower
solute concentration [dilute solution] to higher solute concentration
until a balance is produced. Dilute solutions are highly concentrated
in water and low in solute. Hence, a low concentration of solute
results in a high water potential. The general motion is from more
water to less water or from less solute to more solute.
Osmotic pressure
During osmosis, pressure is generated due to the difference in solute
potentials of two environments separated by a semi-permeable
membrane. This pressure provides the force for the water to move
from low solute concentration to high solute concentration. Once the
water pressure reaches the osmotic pressure, osmosis stops.
Additional Info: Osmosis / Diffusion
The role of osmosis in living organisms
Living cells may be thought of as microscopically small
bags of solutions contained within semi-permeable
membrane that allows water to flow in or out. In order
for the cell to survive, the concentration of solutes
within the cell cannot be changed dramatically. Water
passes through the membrane in both directions to
generate an equilibrium between the cell and its
surroundings. If the cells are in a highly concentrated
solution, the water in the cell would flow out to maintain
the equilibrium between the exterior and interior of the
cell. This may cause the cell to shrink due to loss of
water and die of dehydration. Oppositely, if the cells are
in a more diluted solution, water will enter the cell and
cause it to burst and be destroyed.
Additional Info: Osmosis / Diffusion
Reverse Osmosis
Reverse osmosis is the process by which excess
pressure is placed on one end of a semi-permeable
barrier in order to drive a solution from an area of
high solute concentration to that of a low solute
concentration. Opposite from general osmosis, the
solvent does not go down a concentration
gradient. In this case, the cell membrane serves as
a filter. Reverse osmosis has been used industrially
for water treatment. Salt water collected from the
ocean is transformed to pure water by setting an
external pressure equal to the air pressure at sea
level. Water purification is only one industrial use
of reverse osmosis. Metals and chemicals are also
recycled through this process.
Want to know more?
http://www.youtube.com/watch?v=qucTUoHAeuY&feature=related
Clark College Tutoring and Writing Center tutor Joey Smokey
introduces the concept of diffusion and osmosis, providing
multiple definitions and explaining how the two processes work.
Along the way, he explains things such as concentration gradients,
semipermeable membranes, colloids and suspensions, and the
effects of concentration on red blood cells in isotonic, hypotonic,
and hypertonic solutions.
Related Youtube Videos
http://www.youtube.com/watch?v=0c8acUE9Itw&feature=related
An egg is placed in corn syrup for 60 minutes to show osmosis. The egg is then
placed in fresh water to show the reverse effect.
http://www.youtube.com/watch?v=o6nqYcrItiQ&feature=related
Diffusion: Food Color and Water
http://www.youtube.com/watch?v=2Th0PuORsWY&feature=related
Diffusion through a membrane - Iodine turns blue in reaction to
starch. When a starch solution is placed in dialysis tubing (a semipermeable membrane) and the tubing is added to a beaker of iodine ,
will the starch be able to pass through the tubing and turn the water
blue or will the smaller iodine molecules pass through and turn the
contents of the tube blue?