Strategies
My plan for the curriculum unit is to explore the connection between diabetes and food. This topic is important to help students understand the connection between their eating habits and disease. My overall strategy in designing this curriculum unit is to use hands-on labs experiences that incorporate actual food items. Using food is a great way to stimulate student interest, to help them relate to the topic, and to see that science and biochemistry is not only important in the classroom; it is present in the kitchen as well. By starting at the molecular level of food macronutrients and then progressing to a human system focus, students learn the progressive nature of science, in which concepts continually build on each other.
The unit will start with a consideration of how we measure how much energy is in our food. Students will approach this concept in a lab in which students' burn various foods to determine their calorie content. This process is known as calorimetry. It can be done by putting a volume of water in a soda or tin can and elevating the can on a ring stand. The initial temperature of water is measured and the final temperature of water is measured after the food is burned beneath the water. The change in water temperature reflects the amount of energy in the food, which can be converted into the number of calories in the food. The definition of a calorie is the amount of energy it takes to raise one gram of water 1°C. The Calorie that is seen on nutrition labels is, in fact, a thousand calories or one kilocalorie. By doing this experiment, students should understand that foods with more fats have more calories, and thereby more energy, than less fattening foods.
Biology students have some background knowledge about the basic macronutrients: fats, carbohydrates and proteins that are obtained from food. Students will brainstorm what foods they think have protein, carbohydrates and fats, and then test several mystery foods with chemical indicators to determine which foods have which macronutrients. The chemical indicator solutions we will use are Benedict's solution for simple sugars, Lugol's solution for starch, and Biuret's solution for proteins. Benedict's solution is a chemical indicator that produces a color change from a blue solution to a red, green or yellow color in the presence of simple sugars like glucose. Lugol's iodine turns deep purple to black in the presence of starch. Biuret's solution changes from blue to pink/purple in the presence of protein. Sudan III solution is a chemical indicator that stains lipids a red color.
Following this activity, students will learn through readings and lecture the structure and function of the macronutrients (proteins, fats and carbohydrates). Each day, we will cover a different macronutrient and do an activity for that macronutrient. For protein, we will create a protein using "amino acid" pop beads. The students will continue their study of amino acids by analyzing different protein sources to see which amino acids they contain. Because vegetable sources of protein do not have all the essential amino acids (not synthesized in the body), the students will design a vegetarian meal that will supply all essential amino acids.
For lipids, we will observe the differences in color and viscosity of skim milk, 2% milk, whole milk, half and half and heavy cream and analyze the fat content of these milk products as well. Students will also observe the differences between oil, butter and lard. 42 After writing observations, I will introduce the molecular structures of saturated and unsaturated fats. They will connect the straight chain structure of saturated fats to their solid physical state at room temperature, and the kinky structure of unsaturated fats results in a liquid state at room temperature. I will bring in nutritional labels of certain candy bars so that students can see examples of fats on nutrition labels and learn about partially hydrogenated fats. Hydrogenation is a process to solidify unsaturated fats, in effort to avoid the less healthy saturated fats. Unfortunately, a by-product of this process is trans fats, which are dangerous to health. Most food companies have eliminated trans fats, and trans fats are now banned in New York City.
For carbohydrates, I will use powerpoint lecture to teach the variety of structures that carbohydrates can form from simple monosaccharides like glucose to large polysaccharides like starch and glycogen. Students will analyze different sweeteners like honey, table sugar and fruits for the presence of monosaccharides, disaccharides and polysaccharides using the chemical indicators, Benedict's solution and Lugol's Iodine. In this activity, students can make a direction connection between foods that they eat and enjoy and the study of molecular biology.
The systems portion of this unit will incorporate student research and projects. Students will initially learn the process of digestion through readings, lecture and the use of computer animations. We will focus specifically on the action of the stomach, small intestine, pancreas and liver. They will be able to trace the pathways that each of the nutrients follows through the human body. Specifically, they will be able to answer the questions: where are the nutrients broken down, where are they absorbed and where do the nutrients go in the body? Our focus will be on carbohydrate, in which students will study the physiological response of blood sugar and insulin production after eating carbohydrates (see Image Appendix). To compare how carbohydrates are digested in the body, we will conduct an amylase digestion lab that compares the activity of the enzyme amylase on refined and whole grain carbohydrates in the mouth and in test tubes.
I will use lecture, powerpoint and animations to introduce students to the types of diabetes, the symptoms of the disease, the treatments and the risk that diabetes conveys for other diseases. Each student will then conduct interviews of friends and family, finding out information about that person's individual experience with diabetes and the various treatments and health complications associated with the disease. Students will write the questions that they will ask ahead of time, and after conducting the interview, they will submit an essay about one person's account of living with diabetes.
To complete our study, students will research healthy eating habits that everyone should follow. Students will write what they think that they should eat, and then compare their ideas to Walter Willett's food pyramid. Using the food pyramid, students will work on planning a week's worth of their meals, and research healthy recipes that they would like to eat and prepare. The student's recipes will be compiled into a healthy eating cookbook, and the entire biology class will plan, develop and coordinate a Healthy Food Festival for the entire school.
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