The purpose of this unit is to make EM waves of different wavelengths apparent in students’ everyday lives. This will be accomplished by using devices that students are already familiar with and most likely take for granted ­­–microwave and conventional ovens. Students come into the classroom with the understanding that the microwave oven makes their food hot but without knowing why or how this happens at a molecular level. This unit will give the students real-world context for applications of microwaves and infrared waves.

Understanding wave properties and EM waves is relevant to students because EM waves are used for many purposes and surround us every day. These EM waves are used for technology. There are valid health and safety concerns with exposure to some higher frequency waves, such as ultraviolet radiation, x-rays, and gamma rays. This unit will explore why the microwaves in the microwave oven and infrared radiation from the conventional oven do not have the same safety concerns as the higher energy EM waves.

This curriculum unit, exploring the energy in food and the thermodynamics of cooking, will include 5 days of 80-minute lessons in which the students will pick a particular food to study. The food will either need to be purchased or produced, and will need to be a food that begins as batter or liquid and solidifies during cooking. For those students who, for any reason, cannot bring in the food, they will be provided a brownie, cupcake, or other common food item. The project will contain two main components or parts. First, the energy stored within the food will be analyzed by applying mathematics. This will require conversion between a common physics unit of kilojoules (kJ) and a common household unit of kilocalories (kcal, CAL or Calories). Students will then need to apply their knowledge of work and energy conservation to provide an example of physical exercise that would be required for them to expend an equal amount of energy that is contained in their food. If a student is uncomfortable sharing their own mass, they may use the common example of a 70-kg person. The second part of their project will involve them using experimental data to determine the heat diffusion constant for their particular food by using a method similar to that described by Rowat et al. published in 2014, “The kitchen as a physics classroom10.” This can be done by placing several thermocouples in their food sample (or probing with toothpicks as will be described later) while heating until the center of the food gets to a desired temperature. Once the diffusion constant is determined, it can then be used to derive an equation that will allow the students to determine the required cooking time based on the size of the food sample. Although larger meals may be interesting samples for the experiment, the food samples must remain reasonably small so that the experiment can be completed within a single class period and can be cooked using toaster ovens or small classroom heaters. Students, in groups of 2-3, will be required to share their data with the class so that the results can be discussed. Students will be graded on their mathematical analysis and an accurate derivation of an equation to predict cooking time based on their measured diffusion constant. Teacher checks will be structured strategically throughout the process to ensure student projects meet the requirements and that student groups remain on pace. By relating energy in food to exercises with equal outputs, and by generating equations to ensure foods will be cooked properly, students not only learn physics in an engaging way but also learn how physics can be used to tackle real-world problems.

The main content covered in this unit includes the Structure and Function of the biological molecules, the energy flow and the nutrients, Nutritional Facts Labels, and the My Plate concept. Proteins, nucleic acids, polysaccharides in carbohydrates are considered macromolecules, and the lipid molecules are considered as biomolecules. For clarity purposes, proteins, nucleic acids, carbohydrates, and fats will be referred to as “biological molecules” throughout the unit. The history of studying these biological molecules dates back to the early 19th century. British physician-chemist, William Prout (1785-1850) was the first to classify “foodstuffs or ingredients of life into saccharinous (carbohydrates), oleaginous (fats), and albuminous (proteins)” and urged that “a satisfactory diet should include carbohydrates, fats, protein, and water”3. Carl Schmidt coined the term “carbohydrates” in 1844.