Electromagnetic (EM) waves are all around us, though we can only see a small range of them, they can be used to cook our food, allow cell phones to communicate with each other, and permit us to see inside the human body. This curriculum unit is designed to teach 9th-grade students about EM waves using the microwave and conventional ovens as examples. In this two-week unit, students will learn the physics and chemistry behind how a microwave oven uses microwave radiation and a conventional oven uses infrared radiation to make their food hot.
In order to accomplish this, students will first become acquainted with the electromagnetic spectrum and the idea that the shorter the wavelength, the higher the energy of the EM wave. Next, students will be exposed to how a microwave oven creates and uses microwaves to heat water inside food. Following this will be a lesson on what exactly heat (or thermal energy) is and how heat is related to molecular motions.
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.
Wilbur Cross is a large high school with a diverse student body. Students come from a diverse range of socioeconomic backgrounds as well as many different races and ethnicities. Currently, there are three main instructional foci: HOTs or higher order thinking skills, students to student discourse, and using evidence to support claims. The schedule follows a block schedule with four periods a day and rotating A and B days. Thus, the curricular activities in this unit cater to an 80-minute period. The district's science sequence is that students begin with phychem, then biology and chemistry. After chemistry, there are science electives or advanced placement courses offered.
Students at Wilbur Cross High School are required to take three science courses with phychem as the first in the sequence. Phychem is an integrated science course that focuses on weather and climate, natural resources, wave properties, electricity and magnetism. The course focuses on electromagnetic and mechanical waves in the third marking period with an additional concentration on the application of electromagnetic (EM) waves. Following a unit on mechanical waves and general wave properties, students will be introduced to the EM spectrum.