|  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: breadcrackers
 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 possiblecompleted 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 mgwater
 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 ScienceProject 2061
 1993
 My 
                          Side of the Mountain Author: 
                          Jean Craighead GeorgePuffin 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 HobaMorrow, 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 SzilagyiFranklin 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 WiesnerClarion 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 AndersonFarrar, 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 BarberLawrence 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 LearningJostens 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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