Classroom Activities
Sources of Energy: Building and Breaking Down Food Molecules
Purpose
Students will visualize the structure of the macromolecules and see how they are put together (such as two monosaccharides to create a disaccharide), as well as how they can be broken apart (such as the separation of the glycerol head from the fatty acid tail).
Materials
1 molecular model kit for each pair of students
Diagrams of carbohydrates, fats, and proteins
Directions
Briefly demonstrate how to construct molecules from the molecular kit. It may be valuable to mention that the colors of the molecules are important because the carbon should have four holes corresponding to its ability to form four bonds, the hydrogen one to form one bond, etc. Then provide molecular diagrams of glucose, oleic acid (a fatty acid found in olive oil), and several amino acids bound together (such as glycine and alanine, since they are small). Since proteins are generally more than fifty amino acids in length, it would be nearly impossible to construct a protein in a single class period.
Have the students work together to create two glucose molecules first, then have them join these molecules to make maltose by removing an oxygen and hydrogen from a group on one of the glucose molecules, removing a hydrogen from another, and then joining the two together at the oxygen. The two hydrogens and single oxygen should be bound together to show the release of water from the reaction (condensation). This may be reversed to show the breakdown (hydrolysis).
Next, students should construct oleic acid. Have them construct the glycerol head and then the three fatty acid tails. It may be necessary to shorten the tails if there are not enough materials. Then have them show a series of three hydrolysis reactions to separate the fatty acid tails from the glycerol head. At the attachment point for each fatty acid, add a water molecule so that both the glycerol and the fatty acid has a hydroxyl group where the bond was. The end product should be a glycerol molecule and three separate fatty acid tails. This may be reversed also, to show the formation reactions.
Finally, have the students construct the amino acids alanine and glycine according to the diagrams. They should then link them with a peptide bond; this is also a condensation reaction. Students should remove a hydroxyl group (OH) from one amino acid and a hydrogen to another and then connect the nitrogen of the amine group to the carbon of the former carboxyl group. Remember to have them form water from the hydroxyl and hydrogen that is lost from the amino acids. This will create a dipeptide, one tiny part of a large protein.
Evaluation
Students will show the instructor their molecules and explain the reactions that produced them.
Digestion: Open Inquiry Digestion Lab
Purpose
Students will explore digestion of the different macromolecules through a loosely structured inquiry lab. They will use different digesting agents to visualize and collect data on the breakdown of different carbohydrates, proteins, and fats.
Materials
amylase
pepsin
lipase
hydrocholoric acid (this material and the first three are available through Carolina Biological Company)
whole grain bread (no refined flour)
white bread
hard-boiled egg white
canned tuna
olive oil
butter
test tubes
pipettes
Directions
This is a student-designed inquiry lab, so directions should be brief. Students will be provided with a variety of carbohydrates (two types of bread), proteins (two animal-based sources), and fats (one plant and one animal source). They may bring in additional sources or make requests if they wish. They will also be provided different digestive agents (amylase, pepsin, lipase, hydrochloric acid). Instruct students to design a lab where they can both qualitatively and quantitatively observe and record the digestion of different types of food. Students should take a day to decide on materials and procedure, then take one to two days further to complete the experiment. They will be expected to create a full lab report, including an introduction with background information, hypothesis, materials, procedure, data, analysis, and conclusion.
Evaluation
The lab report will be analyzed on a standard IB laboratory-grading rubric.
Energy Balance: Calculating BMI
Purpose
Students will learn how to calculate the body mass index so that they can have a better understanding whether or not they have a healthy weight. They will also learn that different weights are appropriate for different people and body types, and will understand the risks of being overweight or obese.
Materials
sample students heights and weights (Appendix 1)
calculator
Directions
Students will be given 5 sample student descriptions, including information on their lifestyle as well as their height and weight. Students will then calculate the BMI for each as follows: BMI = [(weight in lbs) x 703)] / (height in in) 2 Students will also provide suggestions on how to improve the sample students' diets. The assumption is that students will be able to make comparisons about their own BMI without asking them to directly calculate it and therefore being more sensitive to the issue of students' weight.
Evaluation
Students will turn in a completed sheet with the BMIs and suggestions recorded on it.
Long-Term Effects of Food: Health Complication Website Project
Purpose
Students will investigate different health conditions that are caused by the choices we make in our diets. This will stimulate thought and discussion on what we can do to make better food choices and how we can avoid these conditions. Students will also broadcast the information they have learned by creating webpages that will be linked to the class webpage. Parents and other students will be encouraged to read the information on these pages in order to make better and more informed nutrition choices.
Materials
laptop computers or computer lab access
access to class website (such as http://pages.google.com)
Directions
Students may choose one condition from the following: nutrient deficiencies (one specifically, such as vitamin B 6 deficiency), obesity, metabolic syndrome, diabetes, and high cholesterol and atherosclerosis. They will then spend two days researching their topic in class using the laptop computers and will be required to come up with the following information: what causes the disorder, what nutrition choices can help prevent the disorder, the effects of the disorder on the body, what the risk factors are (if any, besides diet), treatments or cures, current research, and resources for people at risk. Students should be careful to document exactly where they found their information and use several reliable sources. Students will then provide the information to the instructor, who will load the pages onto the class page, proving useful and applicable health information to other students, instructors, parents, members of the community, as well as general web users.
Evaluation
Students will be assessed in four areas on a rubric: completion, scientific accuracy, neatness and creativity, and documentation (sources).
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