Sweet Science

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Biology In Elementary Schools is a Saint Michael's College student project from a course that ran between 2007 and 2010 and fully described in this book chapter. The student-created resources have been preserved here for posterity. Link under 'toolbox' for printer-friendly versions of the exercises. Click on handouts to print full resolution versions. Please see Wikieducator's disclaimer, our safety statement, and the Creative Commons licensing in English and in legalese.

Student worthiness

Tried and Trusted

Primary biological content area covered

These two experiments assess chemical make up, the human body and health. By testing fat and sugar content we get to see what actually goes into our bodies, allowing us to make smarter food choices.

Materials

Materials for In Class Experiment:

• Safety Goggles
• Latex Gloves
• Bench Coat (or Shower curtain)
• Blunt Probes
• Jar (for the toxic waste)
• Test tubes
• Test Tube Racks
• Droppers
• Benedict's Solution
• Distilled Water
• Hot Plate
• 1000 mL beaker
• Thermometer
• Masking Tape (for labeling)
• Permanent Marker
• Butter/Margarine
• Doughnut
• Apple
• Cereal
• Sugar-Free Gum
• Cream Cheese
• Honey
• Lemon

Materials for Take Home Experiment:

• Sheet of White Paper
• Pencil
• Butter/Margarine
• Doughnut
• Apple
• Cereal
• Lemon
• Honey
• Cream Cheese

• 

  Figure 1. We weighed .5 grams of different food products to test.

• 

  Figure 2. Beginning the experiment by mixing food into water in test tubes.

• 

  Figure 3. Food product mixed with distilled water and Benedict solution immersed in a water bath.

• 

  Figure 4. Results of benedict solution experiment.

Figure 5. Sample Take Home Handout

Figure 6. Finished Take Home Handout

Description of activity

In this activity we aim to use the scientific method to test the fat and sugar content of everyday food products. Students will make predictions as to which foods have the most fat and sugar content. The in-class experiment uses Benedict solution to show a color change when sugar content is present in a food product. The take-home experiment allows the students to test several different foods at one time, comparing the fat residue left on a white sheet of paper. In both experiments students have the opportunity to participate in hands-on testing of the healthiness of their favorite foods. Idea for in class experiment: [[1]]

Lesson plan

Prelab Setup: First measure out 0.5 gram of every food product you plan to test (See Figure 1). Measure out ten drops of Benedict solution and 40 drops of water for each test tube. Test tubes should be labeled according to which food will be placed in it. Also, a jar for the hazardous waste should be labeled to put the excess Benedict solution into after the experiment. Lastly, a hot-plate should be warmed up and a 1000 ML beaker with 500 ML of water should be heated to the temperature of 40 to 50 degrees Celsius. You're ready for Sweet Science!

In Class Activity

• Students will be asked to put on their goggles and their gloves. We will explain to them that they will be working with Benedict solution which is toxic so they should handle the material with care.

• Ask students to predict which food product contains sugar. We will refer to the food pyramid and ask the students where in the pyramid the different foods belong (See Food Pyramid Image). After they make predictions we will explain that Benedict solution will turn to shades of brick-red, yellow and green in the presence of sugar. The solution will remain blue if sugar is not present.

1.In Class Experiment: Sweet Science Each student will be given a test tube and .5 grams of a food product. They will be asked to mush up the food into their test tube and pour the drops of water into their test tube (see Figure 2).

• Students will put their .5 gram of food product into their test tube.
• Put the test tube holder into the hot water bath (40-50 degrees Celcius), making sure no water from the bath gets into the test tubes (See Figure 3).
• Leave the tubes in the bath for 5 minutes. While you are waiting for the color change, begin the take home experiment!

2.Take Home Experiment: Testing Fat Content

• Give students an assortment of food. We will be using the same food products that we tested in the sugar experiment.
• Students take the handout (See Handout 1) and rub or dab the food into the circle with its label.
• The sheets then are left to dry for a few minutes.
• The food with fat content will leave an oily residue on the sheet of paper (See Handout 2).
• Students get to take the handout home to show their parents the fat content of their favorite foods!

3.Conclusion

• Return to the In Class Experiment and observe which foods changed color and which did not (See Figure 4).
• Students get to see the results of their experiment and we will assess if their predictions matched the end product.
• Lastly we will discuss fat in foods and which food we found to be the healthiest.(See Food Pyramid)

Scientific Word Bank

• Variable-The different products that are tested.

• Cross-Contamination-When two separate variables are accidently mixed, this could change the result of the experiment.

• Constant-A constant is something whose value does not change in the course of the problem under investigation.

• Prediction-Making a guess as to the results of an experiment.

• Observation-What you observe/see change or not change in an experiment.

• Measurement-Taking a particular amount of a product.

• Beaker-A beaker is a simple container for stirring, mixing and heating liquids commonly used in many laboratories. Beakers are generally cylindrical in shape, with a flat bottom. Beakers are available in a wide range of sizes.

Sources: [2] [3]

Potential pitfalls

• The Food and Benedict solution could not change rapidly enough to demonstrate the sugar content to the students.
• The water could not heat to the proper temperature to make the change occur.
• The food could spoil and we could not have anything to present.
• If one of the students was allergic to one of the food products we tested.

Health Connection

Here is the new and improved food pyramid! This is what we used in the in class activity.

http://pub.etr.org/upimages/newpyramid.gif Source for Image: [[4]] Figure 7. Food Pyramid

Math Connections

Fahrenheit to Celsius Conversion

• Students for this experiment had to heat water to 40-50 degrees Celsius. Most students are used to seeing and hearing about temperatures in Fahrenheit. Teachers can explain the conversion of Fahrenheit to Celsius while doing the pre-lab, heating the water to a particular temperature in order for the change to occur.

Source for Celius Information: [5]

History connections

Benedict's reagent (also called Benedict's solution or Benedict's test) is a chemical reagent named after an American chemist, Stanley Rossiter Benedict. Benedict's reagent is used as a test for the presence of all monosaccharides, and generally also reducing sugars. These include glucose, galactose, mannose, lactose and maltose. Even more generally, Benedict's test will detect the presence of aldehydes (except aromatic ones), and alpha-hydroxy-ketones, including those that occur in certain ketoses. Thus, although the ketose fructose is not strictly a reducing sugar, it is an alpha-hydroxy-ketone, and gives a positive test because it is converted to the aldoses glucose and mannose by the base in the reagent.

Source for Benedict reagent history connection: [6]

Literary Connection

The Race Against Junk Food :Adventures in Good Nutritionby Anthony Buono (Author) Roy Nemerson (Author) and Brian Silberman (Illustrator) Published: HCOM Inc. c1997.

For a Book Review of The Race Against Junk Food: http://www.naturalnews.com/017329.html

Connections to educational standards

VERMONT STANDARDS 7.14 PreK-4: The Human Body: Students demonstrate understanding of the human body--- heredity, body systems, and individual development---and understand the impact of the environment on the human body. This is evident when students: c. Identify and describe environmental factors that can influence human health (e.g., exposure to microbes, pollution.

Source for Vermont Standards: [[7]]

Next steps

When doing a unit on health and a healthy diet there are endless opportunities to bring in different activities. One of the main materials that we found to be very helpful was the new food pyramid. Students can learn a lot by focusing on the different parts of the food pyramid and creating lessons focused on what it is trying to teach. We based our lesson on fat and sugar testing, thus looking mostly to the oil/sugar, fruit and grain section of the food pyramid. However, a teacher could also create a lesson on the new addition of exercise to the food pyramid (the small man running up the side). By expressing to students that sugar/fat intake is okay as long as a student is active, students will realize the importance of a balanced lifestyle which is important to learn at an early age. A teach could also base the fat test on what the students like to eat. In our lesson we had to pick a diverse selection of food and were not sure what the students actually like to eat. However, by inviting the students to bring in some of their favorite foods, the fat test will be geared more towards their everyday food intake and they will learn about things they like to eat. A few of the students also asked why we were not testing peanut butter or butter like we had originally planned, these questions presented a great opportunity to discuss food allergies and why it is important to be aware of other people's sensitivities to food. Students could have a discussion on different foods they are allergic to and the teacher could create a lesson on why we develop allergies and how they affect different people. There are many ties from this lesson plan to health and a healthy diet that could be useful for students to learn about at the elementary level.

Reflections

Overall, I think that the experiment went extremely well! The students seemed very engaged and interested in the subject matter and were willing to learn. I think this experiment went so well was because it was very hands on. The students loved getting messy! The fat content experiment allowed the students to rub the food themselves on their on sheets of paper which they seemed to have a lot of fun doing. I also saw that they liked the fact that they were working with toxic materials (but they never actually handled them). Something that was unexpected for me was how well behaved the children were. For the most part every child was cooperating and engaged in the activities presented to them. They raised their hands when asked questions and were attentive given instructions or discussing the subjects. The majority of the students had a good amount of prior knowledge about fat/sugar content in food. They knew some facts about the new food pyramid and for the most part could tell which foods were unhealthy/healthy. They also had prior knowledge about what a hypothesis is and the students all had no problem coming up with their own hypotheses. This complimented the lesson very well so that it was easier for myself and Shelby to teach it. I also think that because the students had some prior knowledge about fats and sugars we did not have to waste time in in-depth description of every little aspect of the lesson.

A "must do" for this experiment for this lesson plan is discussing the new food pyramid and allowing the students to get messy rubbing the different foods onto their fat testing sheets. These two elements kept the students engaged and connected to their daily lives. Also, it worked extremely well to have the students record which food they thought would react to the Benedict solution. When the students made predictions they were more likely to pay attention to the results to see how well they hypothesized.

Citations and links

1.http://www.sciencecompany.com/sci-exper/food_chemistry.htm#Benedict's%20Solution 2.http://en.wikipedia.org/wiki/Beaker_(glassware) 3.http://en.wikipedia.org/wiki/Variable 4.http://pub.etr.org/pages.aspx?docid=176 5.http://en.wikipedia.org/wiki/Celsius 6.http://en.wikipedia.org/wiki/Benedict_solution 7.http://www.education.vermont.gov/new/html/pubs/framework.html