Testing
for Vitamin C in different drinks and foods
Developers:
Brenda
Ortiz
Fairhill Elementary School
School District of Philadelphia
Philadelphia, PA
Dottie
Reed
Walton Farm Elementary School
North Penn School District
Lansdale, PA
Enrique
Michelotti, Ph.D.
Rohm and Haas Company
Spring House, PA
Paul
Reibach, Ph.D.
Rohm and Haas Company
Spring House, PA
Grade
Level:
2
through 6
Disciplines:
Physical
Science (Chemistry), Health (Nutrition), Math, Language
Arts, Social Studies
Goals:
Students
will:
1.
develop an understanding of the importance of Vitamin
C in their diet.
2.
learn sources of Vitamin C.
3.
develop an awareness of the use of Vitamin C in helping
our environment.
4.
gain exposure to chemical procedures and techniques.
5.
analyze and interpret data by keeping a data sheet and
making a bar graph.
6.
have many opportunities for hands-on science activities.
7.
keep a science notebook throughout the unit.
8.
learn that science can be fun!
Background:
These
activities on Vitamin C testing can be used to strive
towards the following Benchmarks for Science Literacy
(see bibliography):
By
the end of second grade, students should know that:
1B
- People can often learn about things around them by
just observing those things carefully, but sometimes
they can learn more by doing something to the things
and noting what happens.
- Describing things as accurately as possible is important
in science because it enables people to compare their
observations with those of others.
1C
- In doing science, it is often helpful to work with
a team and to share findings with others. All team members
should reach their own individual conclusions, however,
about what the findings mean.
2C
- Numbers and shapes can be used to tell about things.
4C
- Change is something that happens to many things.
4D
- Objects can be described in terms of the materials
they are made of (clay, cloth, paper, etc.) and their
physical properties (color, size, shape, weight, texture,
flexibility, etc.)
- Things can be done to materials to change some of
their properties, but not all materials respond the
same way to what is done to them.
6D
- People can learn from each other by telling and listening,
showing and watching, and imitating what others do.
6E
- Eating a variety of healthful foods and getting enough
exercise and rest help people to stay healthy.
8E
- Letters and numbers can be used to put things in a
useful order.
9A
- Numbers can be used to count things, place them in
order, or name them.
- It is possible (and often useful) to estimate quantities
without knowing them exactly.
- Simple graphs can help to tell about observations.
9B
- Sometimes changing one thing causes changes in something
else. In some situations, changing the same thing in
the same way usually has the same result.
9D
- Some things are more likely to happen than others.
Some events can be predicted well and some cannot. Sometimes
people aren't sure what will happen because they don't
know everything that might be having an effect.
11C
- Things can change in different ways, such as in size,
weight, color, and movement. Some small changes can
be detected by taking measurements.
12A
- Raise questions about the world around them and be
willing to seek answers to some of them by making careful
observations and trying things out.
12D
- Describe and compare things in terms of number, shape,
texture, size, weight, color, and motion.
- Draw pictures that correctly portray at least some
features of the thing being described.
12E
- Ask "How do you know?" in appropriate situations
and attempt reasonable answers when others ask them
the same question.
By
the end of 5th grade, students should know that:
1B
- Scientific investigations may take many different
forms, including observing what things are like or what
is happening somewhere, collecting specimens for analysis,
and doing experiments. Investigations can focus on physical,
biological, and social questions.
- Results of scientific investigations are seldom exactly
the same, but if the differences are large, it is important
to try to figure out why. One reason for following directions
carefully and for keeping records of one's work is to
provide information on what might have caused the differences.
- Scientists do not pay much attention to claims about
how something they know about works unless the claims
are backed up with evidence that can be confirmed and
with a logical argument.
1C
- Clear communication is an essential part of doing
science. It enables scientists to inform others about
their work, expose their ideas to criticism by other
scientists, and stay informed about scientific discoveries
around the world.
- Doing science involves many different kinds of work
and engages men and women of all ages and backgrounds.
2A
- Mathematical ideas can be represented concretely,
graphically, and symbolically.
6C
- From food, people obtain energy and materials for
body repair and growth. The indigestible parts of food
are eliminated.
6D
- Humans can use the memory of their past experiences
to make judgments about new situations.
6E
- Food provides energy and materials for growth and
repair of body parts. Vitamins and minerals, present
in small amounts in foods, are essential to keep everything
working well. As people grow up, the amounts and kinds
of food and exercise needed by the body may change.
- Tobacco, alcohol, other drugs, and certain poisons
in the environment can harm human beings and other living
things.
9B
- Tables and graphs can show how values of one quantity
are related to values of another.
9D
- Some predictions can be based on what is known about
the past, assuming that conditions are pretty much the
same now.
12A
- Keep records of their investigations and observations
and not change the records later.
12C
- Measure and mix dry and liquid materials in prescribed
amounts, exercising reasonable safety.
- Keep a notebook that describes observations from ideas
and speculations about what was observed, and is understandable
weeks or months later.
12D
- Make sketches to aid in explaining procedures or ideas.
-
Use numerical data in describing and comparing objects
and events.
Introduction:
Many
students know that vitamins are important to their health.
However, they may not know why. Because vitamins cannot
be experienced through the senses, students may not
know that foods they may commonly eat contain vitamins.
They also may not understand the importance of vitamins
in their diets.
Ascorbic
acid, commonly known as Vitamin C, is important to the
human diet. It helps the body form connective tissue,
bone, teeth, blood vessel walls, and assists the body
in assimilating iron and amino acids. A diet deficient
in Vitamin C may cause a person to develop scurvy. Symptoms
of this disease, which include joint stiffness, nose
bleeds, swollen and bleeding gums, livid spots on skin,
and prostration (extreme physical weakness), can be
prevented by adding Vitamin C to one's diet. Plants
and some animals make their own Vitamin C, but humans
do not. For this reason, humans need to seek Vitamin
C from other sources.
Vitamin
C is also an anti-oxidant. This means that it will help
prevent oxidation. Consider foods that contain little
or no Vitamin C, such as apples and bananas. After exposure
to the air, these fruits turn brown. Now consider foods
that contain a large amount of Vitamin C, such as oranges,
lemons, and limes. When these fruits are exposed to
the air, they do not turn brown. This is due to Vitamin
C's ability as an anti-oxidant. (Students will observe
this phenomena in Activity #7.)
Children
and adults should gain knowledge as to why they need
to choose foods rich in Vitamin C, not just the "junk
food" they enjoy eating. They should also learn
that there are things we cannot see contained in foods
and other things around us. Most people are probably
unaware that in the United States, 60 milligrams of
Vitamin C is the recommended daily allowance. The following
lessons and experiments can be used to introduce children
to this knowledge in an exciting manner.
In
some of the experiments, a commonly used hands-on laboratory
technique known as titration will be introduced to students.
A titration involves adding one solution dropwise into
another solution until a color change is observed. When
a color change is noted, the titration process has reached
the end point.
In
order to perform the titrations, an indicator solution
is usually used. Two different indicators are described
in this unit, but only one needs to be used. The two
indicators are indophenol, and cornstarch-iodine solution.
Both indophenol and iodine are dangerous substances.
However, with much caution and supervision, any problems
can be avoided.
Indophenol
is a blue powder, which is mixed with water to form
a deep blue indicator solution. The color changes (blue
to purple to pink to colorless, and various shades in
between) that can be observed during a titration using
indophenol are vivid and exciting. However, indophenol
is a toxic substance, and the indophenol solution should
be made by the teacher, not the students. Students should
wear gloves and safety goggles when handling indophenol
solutions. Disposal of the waste solutions containing
indophenol may also be a problem. It should not be poured
down a school drain. If you plan to use the indophenol
solution, check with your school, area colleges, local
chemical companies, or your local government for advice
or information on collection possibilities before you
begin these experiments. Indophenol must be purchased
through a chemical supplier. Also, if you plan to use
indophenol instead of the cornstarch-iodine solution,
you may skip Activity #1, which is a starch test that
will help introduce the alternate indicator solution.
Iodine
is also a toxic chemical, but has less potential dangers.
It is a common household item, which is often used on
skin to help heal cuts. Iodine and cornstarch are both
easily available in supermarkets, and iodine can also
be found in drugstores. Because iodine is used on the
skin, gloves are not necessary, though they are helpful.
The cornstarch-iodine solution can be made by the students
themselves, allowing them to exert more power and independence
in the experiment. The color change observed may not
seem as exciting as that observed using indophenol,
but it can still be quite intense. The cornstarch-iodine
solution may be poured down the drain, though you may
still want to check with your school before doing so.
Cornstarch
is a household food item, and does not pose any potential
dangers in classroom use.
Activity
1: Testing for Starch
(Possible
activity prior to testing for Vitamin C. Complete this
activity if you plan to use the cornstarch-iodine solution
for testing for Vitamin C.)
Objectives:
Students
will:
1.
learn a chemical testing procedure for the presence
of starch in a food.
2.
recognize by color which foods contain starch.
3.
participate in hands-on activities.
4.
learn that science can be fun.
Background:
Foods
that contain starch will turn a blue-black when a drop
or several drops of the indicator are added to the food.
The more starch a food contains, the deeper the color
will appear. The teacher can add other foods containing
starch that students do not bring in, or students can
investigate on their own on another day. Examples of
foods containing starch include potatoes, rice, and
cornstarch. Paper contains starch to make it stronger
and smoother. Confectioner's sugar contains starch to
prevent caking.
Iodine
is a poison and discussion with students at this time
as to safety precautions is most important. Also, discuss
the method of disposal for the food samples.
Materials:
bread
crackers
potatoes
other foods or items that contain starch (see background)
paper towels
tincture of iodine
samples of food to be tested, brought by the students
pipets, eyedroppers, or straws (one for each student)
(You
may use a straw in place of a pipet by placing one end
of the straw into the solution and your finger over
the other end. To transfer the solution from the straw
to a food, keep your finger on the straw until you are
ready to release the solution.)
Procedure:
1.
Children put samples of food to be tested on their paper
towel.
2.
If this is their first time using a pipet, instruction
will need to be given so students can get only
one drop at a time on their food samples. (It might
be helpful to practice with water if additional
pipettes are available.)
3.
Students should allow a few drops of iodine to fall
directly on the sample and observe the results.
Students
should record the results of each sample of food by
writing and/or drawing in their notebook.
Critical
Thinking Questions:
1.What
samples contain starch?
2.How
can you tell which samples contain starch?
Activity
2: Testing for Vitamin C in Juice
Objectives:
Students
will:
1.
demonstrate the chemical procedure of titration.
2.
learn that the end point of titration will be a colorless
solution.
3.
discover sources of Vitamin C.
4.
collect data as to how many drops were needed for the
indicator to become colorless.
5.
participate in hand-on activities.
6.
learn that science can be fun.
Background:
The
chemical procedure of titration will be used to test
for Vitamin C. Titration involves adding a test liquid,
drop by drop, to an indicator solution that undergoes
a series of color changes as Vitamin C is added to it.
Students will work with a partner recording the number
of drops required to change the color of the indicator.
The point at which the indicator becomes colorless is
called the end point.
Two
different indicators will be shared.
Cornstarch-iodine
solution - Even though iodine is a poison, it
is used in water treatment and much safer for children
to use and dispose of. On a previous day the teacher
should make the cornstarch-iodine solution. Mix 2 tablespoons
of cornstarch in 500 ml of water to make a cornstarch
solution. Filter the starch solution through 2 to 4
of the thicker brand paper coffee filters until you
have a clear liquid. The solution may be clear to slightly
cloudy, but should not be milky white. Now add tincture
of iodine by drops with constant stirring until the
solution turns a deep, dark blue. If you add too much
iodine, the solution will become brownish.
Di-chloro-indophenol
solution - The indophenol
solution used in class is so dilute that it is safe
for students to use. However, the concentrated powder
can be harmful, and you will need to be careful not
to get the powder on your skin or in your eyes when
mixing the solution. Tell the students to avoid getting
the indophenol solution on their skin. If they do get
some solution on their skin, they should wash the area
immediately. Caution all students against tasting anything
in the science lab. Also, do not allow students to pour
any chemicals down the drain. They should be poured
into a proper receptacle. Contact your school district,
a chemical company, or township recycling for proper
disposal. To prepare the indophenol indicator, use a
flat, wooden toothpick as a scoop. From the wide end
of the toothpick, mark a half inch (1.25 cm). Place
the toothpick into the indophenol powder up to the mark
and scoop up as much powder as will fit on that area
of the toothpick. Place ten toothpick scoops of indophenol
in a gallon container and fill with tap water. Test
the approximate concentration of the solution by adding
a few drops of fresh orange juice to about 10 ml of
indophenol solution. The indophenol solution should
become colorless with about 4-8 drops of juice. Fewer
drops indicate a dilute solution (add a scoop of indophenol),
and more than 8 drops indicates a solution which is
too concentrated (add more water). This solution should
be stable for about a month, and should be enough to
complete the tests with a class of about 25-30 students.
Both
solutions will work for Vitamin C testing. Though the
colors of the two solutions are about the same, the
intensity of the indophenol is much brighter than that
of the cornstarch-iodine solution.
Make
sure you "swirl" the indophenol/cornstarch-iodine
solution after the addition of each drop of juice. (A
swirl is when you hold the container at the top and
circle the bottom of the container to stir the liquid.)
Make
sure that all bottles are labeled.
This
lesson could be completed over several days. Day 1 could
include a teacher demonstration of titration, with students
repeating it as modeled. Other days could involve the
testing of various juices.
Materials:
cornstarch-iodine
solution or indophenol solution. Pour 10 ml of the indicator
solution into clear glass or plastic vials or containers.
One container for every 2 students, but a new container
of solution will be needed for every titration test.
container
of 500 ml of water in which a 500-mg Vitamin C tablet
has been dissolved.
a
variety of juices, including juices with and without
Vitamin C (avoid using red or purple colored drinks
- see the procedure) (Students can bring the juices
in from home.)
pipets
- 1 for each pair of students
white
construction paper - 1 sheet for each pair of students
data
sheet - 1 for each student
Procedure:
- The
teacher will demonstrate the technique of titration
and end point using a vial of indicator and dissolved
Vitamin C tablet.
- Using
a clean pipet, drop one drop at a time of juice into
the indicator solution. One student can hold the vial
of indicator solution, while the partner adds one
drop of the dissolved Vitamin C tablet solution.
- The
teacher should observe and swirl the container as
a model for the students. Students must count each
drop of juice that is added to the indicator until
the indicator is colorless against a white background.
This is the end point. (Please note: artificial colors
in some drinks may tint the colorless solution. Avoid
using red or purple colored juices, as it may be extremely
difficult to see a color change in the indicator.)
-
Demonstrate how students should record their results
on their data sheet.
- Using
the juices, students in groups of two should repeat
this same experiment as modeled. The teacher will
be observing the students, checking for their ability
and understanding of the use of titration and end
point.
- Students
are now ready to titrate and test fruit juices for
Vitamin C. Review the necessity for accurate note
keeping using the data sheet.
Critical
Thinking Questions:
1.
Discuss the results of their experimentation. Possible
questions may include: How many drops did it take to
titrate the indicator with the Vitamin C solution? How
many drops did it take to titrate the indicator with
orange juice?, and How many drops did it take to titrate
a juice with very little Vitamin C?
2.
What is the relationship between the number of drops
of juice needed to titrate the indicator solution and
the amount of Vitamin C in the juice? (The fewer drops
required to titrate the indicator, the greater the amount
of Vitamin C in the liquid.) (This may be confusing
to some students, especially the younger ones, but more
experimenting and other activities should reinforce
this relationship and make it less confusing.)
Activity
3: Analyzing and Graphing the Results
Objectives:
Students
will:
1.
develop skills in analyzing and interpreting data.
2.
use a calculator to find averages.
3.
make a bar graph to show their results.
4.
learn scientific and nutritional information about Vitamin
C.
Background:
The
students will combine data from Activity 2, calculate
averages, and construct a bar graph. Make one copy of
the graphing sheet for each student. (Older more experienced
students can make their own bar graph.) If an overhead
transparency will be used to guide students with graphing,
make necessary preparations ahead of time.
Materials:
calculators
- 1 for each student, if possible
completed data sheets from Activity 2
graphing sheets - one per student
colored pencils or crayons
optional: overhead projector and transparency
Procedure:
1.
In a class activity, the teacher will make a list of
each drink that was tested on the board or chart paper.
2.
As the teacher goes through each drink listed, each
group will report how many drops of the drink were needed
to titrate the indicator, and the teacher will record
that on the board next to the name of that drink.
3.
Students may notice that different groups have different
results, even though they have tested the same juice
samples. Have students explain why they think this occurs,
and ask them what they think scientists would do if
they had different results for the same experiment.
Explain to students that scientists may redo the experiment,
or they may investigate to find if there were any differences
in the experimental procedure. They may also average
their results, which is what the students are about
to do.
4.
Have students average the class results using a calculator.
If students do not know how to compute averages, you
may want to explain how to do them and allow the students
to practice.
5.
Have the students report the average results for each
drink as the teacher writes the averages on the board
or chart paper next to the name of each drink.
6.
Students will use the average results for each drink
to make a bar graph. If students do not know how to
make a bar graph, demonstrate by using the first drink
listed on the board or chart paper, writing the name
of the drink on the graph sheet, and coloring in a block
for each drop that was needed to titrate the indicator
(remember to use the average result). Now have students
work in pairs to complete the graph sheet.
Critical
Thinking Questions -
1.
Have the students rank the juices in order from the
juice containing the most Vitamin C to the juice containing
the least amount of Vitamin C. Remind students that
the more Vitamin C a drink contains, the lower the number
of drops it takes to titrate the indicator.
2.
In their notebooks, have students describe what the
results mean to them, and what conclusions they can
make from the results. (They may describe what drinks
they would choose if they wanted the most Vitamin C,
and which they would avoid.)
3.
Why do we need Vitamin C in our diet? (See background
material in the introduction of this article.}
Activity
4: Testing Fruit and Food for Vitamin C
Objectives:
Students
will:
1.
learn alternative sources of Vitamin C.
2.
practice the technique of titration.
Background:
See
Activity 2: Testing for Vitamin C in Juice
Materials:
a
variety of fruits, vegetables, and potatoes (Try to
include a mix of foods that do and do not have Vitamin
C such as oranges, apples, strawberries, bananas, lemons,
tomatoes, etc.)
indicator
solution (cornstarch-iodine or indophenol)
blender
coffee
filter paper
pipets
Procedure:
1.
Make solutions for each food either by squeezing the
juice directly from the foods (such as with oranges
and lemons), or by blending with water and filtering
the pulp of the food through coffee filter paper. Place
each food sample in a different, labeled container.
2.
Pour indicator fluid into enough bottles to test each
food sample.
3.
Titrate food samples into the indicator solution dropwise,
counting the number of drops needed
to reach the endpoint of the titration.
4.
Record your data.
5.
Graph the recorded data.
Questions
for Critical Thinking:
1.
Which foods contain the most Vitamin C?
Journal
Writing:
2.
If you were planning a meal rich in Vitamin C for your
family, which foods would you want to include?
Activity
5: Another Vitamin C Test using Potatoes
Objectives:
Students
will:
1.
learn sources of Vitamin C
2.
participate in hands-on activities.
3.
learn that science is fun.
Background:
In
Activity 1, students learned that potatoes contain starch.
In Activity 4, they learned that potatoes also contain
Vitamin C. In this experiment, instead of using titration,
the students will put the potato slice in the indicator
solution and mash it until the indicator becomes colorless.
Materials:
For
each pair of students:
indicator
solution (cornstarch-iodine or indophenol) in a clear
container
a
slice of potato (Idaho potatoes work best for mashing)
utensil
for mashing (i.e. wooden skewers)
Procedure:
1.
Place potato slice in indicator solution, which should
be blue.
2.
Begin to mash the potato in the solution until the blue
indicator solution turns clear. This color change indicates
the presence of Vitamin C.
(Precaution:
Avoid splattering of indicator solution. Caution children
against vigorous mashing to avoid splattering of indicator
solution. Eye goggles are a must!)
Questions
for Critical Thinking:
1.
Should potatoes be considered an important part of many
meals? Why?
Activity
6: Analysis of Vitamin C Lozenges
Objectives:
Students
will:
1.
develop an understanding of the importance of Vitamin
C in their diet.
2.
name a commercial source of Vitamin C.
3.
participate in a hands-on activity.
4.
learn that science is fun.
Background:
This
lesson provides an opportunity for students to learn
that in the United States, the recommended daily allowance
(R.D.A.) of Vitamin C is 60 milligrams. In today's society,
you may purchase lozenges that contain the U.S.R.D.A.
of Vitamin C.
Materials:
Vitamin
C lozenges, 60 mg
water
indicator solution (cornstarch-iodine or indophenol)
pipet
Procedure:
1.
Dissolve the lozenge in 60 ml of water.
2.
Pour the indicator solution in a separate container.
3.
Children should predict how many drops will be needed
to reach the end point.
4.
Using a pipet, add the lozenge solution to the indicator
bottle dropwise.
5.
Count and record the number of drops needed to observe
a color change in the indicator solution.
Optional:
If you are using indophenol as the indicator, you may
want to save one titrated indophenol solution for reoxidation
using an aquarium air pump. This may revert the color
of the solution to blue. In a less concentrated solution,
this may also occur in the bottle of solution overnight
without the use of the air pump.
Questions
for Critical Thinking:
Journal
writing:
1.
Why would manufacturers produce a lozenge that you can
carry on your person?
2.
Why would manufacturers produce a lozenge that contains
exactly 60 mg of Vitamin C?
Activity
7: Food Oxidation Tests
Objectives:
Students
will:
1.
develop an awareness of the use of Vitamin C in helping
our environment.
2.
participate in hands-on activities.
3.
learn that science is fun.
Background:
In
previous activities, students learned that potatoes
contain Vitamin C. In this activity, students will learn
that potatoes and some other foods do not contain enough
Vitamin C to prevent oxidation (which will cause them
to turn brown). In Part A of the Procedure, both sets
of potatoes will eventually turn brown due to oxidation.
The slow rate of oxidation of the potatoes covered with
ascorbic acid powder is due to the ascorbic acid (Vitamin
C), which is an anti-oxidizing agent. (Please refer
to paragraph #3 of the Introduction.) Students will
see how Vitamin C can be useful to our environment by
protecting food from oxidation. Note: Apples may contain
preservatives for shipping purposes, which may deter
the apple from browning.
Skit:
To
help students understand the processes of oxidation
and anti-oxidation that will be observed in this activity,
they may perform the following skit. The teacher should
prepare (or have the students prepare) signs (1 for
each person) with one of the following words: ASCORBIC
ACID (VITAMIN C), POTATO, APPLE, BANANA, and OXYGEN.
Part
1
Each
student holds up their sign and acts out their part
as the teacher narrates what will happen in the process
of oxidation, and then anti-oxidation. Students portraying
the roles of POTATO, APPLE, and BANANA will assume a
position somewhere in the classroom. Those students
portraying the role of OXYGEN will surround the foods,
and "attach" to them by holding their hands.
This represents oxidation. Students may return to their
seats for a discussion.
Part
2
Foods
will assume their original skit positions, but this
time, those portraying the role of ASCORBIC ACID will
"attach" to the foods by holding their hands.
OXYGEN will try to penetrate the foods, but they will
not be able to "attach" to them because ASCORBIC
ACID is already attached, and will prevent the oxygen
from attaching to the foods. This represents anti-oxidation.
Students will return to their seats for a discussion.
Now
students will have an opportunity to witness these processes
through a hands-on experiment.
Materials:
Part
A
For
each pair or group of students:
potato
pieces, mashed up and divided into two separate containers
(Idaho potatoes work best)
ascorbic
acid (Fresh Fruit brand powder)
Part
B
For
each pair or group of students:
1
apple
1
potato (Idaho potatoes work best)
1
banana
1
lemon or lemon juice (use with a pipet)
ascorbic
acid powder (Fresh Fruit brand powder)
knife
(should be used by the teacher, not the students)
Procedure:
Part
A
1.
In one container of mashed potato, cover the potatoes
with the ascorbic acid powder.
2.
Do nothing to the other container of mashed potatoes.
3.
Let the two containers sit for a while.
4.
Notice any changes and continue to check on the potatoes
every 15 minutes or so, recording
your observations.
Part
B
1.
Cut the apple, potato, and banana in thirds.
2.
Sprinkle 1 third of the apple, the potato, and the banana
with ascorbic acid powder.
3.
Sprinkle 1 third of the apple, the potato, and the banana
with the lemon juice.
4.
Leave the final third uncovered.
5.
Leave the food slices exposed to the air overnight.
6.
Next day, examine the food slices for browning, due
to oxidation, and record your results.
Please
note: Oxidation is an irreversible process. Make sure
students understand that once fruits have been browned
(due to oxidation), adding ascorbic acid powder will
not return the foods to their original freshness.
Questions
for Critical Thinking:
Journal
writing
1.
Tell what the results of this experiment mean to you.
2.
How could we model the oxidation of food in a labeled
drawing? (Refer students to the skit.)
Assessments:
Pre-assessment
- To find out what your students know about Vitamin
C, you can use a KWL chart. KWL represents What you
Know, What you Want to know, and What
you Learned. This can be completed individually
or as a class.
On-going
assessment - The teacher should be listening, observing,
asking questions, and possibly using a checklist to
keep account of student achievement.
Post-assessment
- Several assessments have been included here for your
choice.
1.
Students can complete the L part of the KWL chart.
2.
"What are the Big Ideas (important concepts) that
you feel are important from our study of Vitamin C?"
(This could be discussed with the entire class or as
an individual assignment.)
3.
A more formal written assessment is included. This could
be changed to suit your needs.
-
You are eating corn-on-the-cob and wonder if it contains
starch. Describe how you would test the corn to see
if corn has starch in it. Use drawings to help explain
your description. (Use this assessment only if you
used the cornstarch-iodine solution.)
-
Explain the process of titration so a new student
can test for Vitamin C.
-
Write an advertisement for a radio show telling why
Vitamin C is important to human health.
-
Make a list of foods you would suggest to your parents
to make sure your family gets its recommended daily
requirement of Vitamin C.
4.
Checklist or Rubric
-
Worked cooperatively with partner.
-
Completed his/her science notebook and made labeled
drawings.
-
Participated in class discussions.
-
Demonstrated the chemical process of titration.
-
Explained what was done.
-
Made reasonable predictions.
-
Followed directions.
-
Completed a graph.
-
Analyzed and interpreted data.
Teacher
and Student Resources:
Benchmarks
for Science Literacy
American
Association for the Advancement of Science
Project 2061
1993
My
Side of the Mountain
Author:
Jean Craighead George
Puffin Books, Viking Penguin, New York 1991
E.P. Dutton, New York 1959
Grades:
5-12
This
story tells of a boy's adventures alone in the mountains
of New York. He suffers symptoms of scurvy (a Vitamin
C deficiency), such as nosebleeds, during the winter
as his food is running out. This experience is described
in depth on page 142 (Penguin) or page 134 (Dutton).
This
book won the Newberry Honor, ALA Notable Book, and the
Hans Christian Andersen International Award.
*
This story would be an excellent introduction into investigating
Vitamin C. Just be aware that the scurvy section is
toward the end of the book. Students really enjoy the
story.
There
is a video of the story, which is excellent, but does
not include the Vitamin C deficiency section.
Russell
Sprouts
Author:
Johanna Hurwitz; Illustrated by Lillian Hoba
Morrow, New York 1987
Viking Penguin, New York 1989
Grades:
1-4
In
this last chapter, "The Science Project",
Russell's first grade class learns about plants and
vitamins. Since potatoes contain Vitamin C, Russell
chooses to sprout a potato. His positive attitude that
science is fun involves his whole family in his project.
*
This is an easy chapter book that could be used as an
introduction to the study of Vitamin C, especially for
younger students.
Oranges
Author:
Zack Rogow, Illustrator: Mary Szilagyi
Franklin Watts, New York 1988
Grades: K-5
In
this book, the process of taking an orange from the
tree through getting it to one's home is described.
The
book also tells how people must work together so that
people in all areas and during all seasons may have
constant sources of Vitamin C rich foods.
June
29, 1999
Author:
David Wiesner
Clarion Books, Houghton Mifflin Co., New York 1992
Grades: 3-6
As
a science project, Holly grows vegetable seeds in space.
Students may realize from this book that sometimes there
may be unexpected experimental results.
Elliot's
Extraordinary Cookbook
Author:
Christine Bjork, Illustrator: Lena Anderson
Farrar, Straus & Girroux, New York 1990
Grades:
3-6
This
is a good book for teaching about food and nutrition.
With the help of a neighbor, Elliot cooks wonderful
recipes, and investigates foods that are healthy and
not healthy. Elliot also learns about proteins, carbohydrates,
the history of chickens, and how cows produce milk.
Vitamin
C Testing, Teacher's Guide
Author:
Jacqueline Barber
Lawrence Hall of Science, University of California,
Berkeley, California 1988
Grades:
4-8
This
book gives a complete investigation of Vitamin C testing
using the chemical indophenol.
The
Science Chef
Authors:
Joan D'Amico and Karen Eich Drummond, R.D.
Illustrator: Tina Cash-Walsh
John Wiley & Sons, New York 1995
Grades:
2-6
This
book contains 100 fun food experiments and recipes for
kids. It answers the question, "Why does a cut
apple turn brown?", with an experiment preventing
browned fruit. Then there are four recipes using orange
juice to prevent the fruits being used from turning
brown. Another experiment related to this theme answers
the question, What's so special about potatoes? This
is a good book for teacher and students.
Kitchen
Chemistry
Authors:
John Bath, Ph.D. and Sally Mayberry, Ed.D.
Illustrated: Catherine Yuh
Carson-Dellosa, NC 1994
Grades:
4-6
This
book contains 39 basic science experiments designed
around readily available, inexpensive materials found
in the home. Two experiments related to this theme would
be Testing for Vitamin C and Testing for Starch. Younger
children could complete these experiments under proper
guidance.
First
Connections, CD-ROM Children's Encyclopedia
A
Renaissance in Learning
Jostens Learning
Under
Vitamins and Minerals there is information that would
be quite suitable for students to find and read.
Web
Sites:
http://www.apsu.edu/sites/apsu.edu/files/chemistry/SP11_1021_ANALYSIS_OF_VITAMIN_C.pdf
- Analysis of Vitamin C
http://chem.lapeer.org/Chem1Docs/VitCAnalysis.html - Analysis of Vitamin C
http://chemmovies.unl.edu/chemistry/beckerdemos/BD047.html
- Vitamin C in Fruit Juices
This experiment is courtesy of 
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