The main purpose of this unit is to explore the chemical, physical and engineering concepts that take place in cooking as a means of assisting students to make and apply concrete connections of these principles to their daily lives. Thus, the goal is for students to understand that physical, chemical, and biological changes are not a bunch of abstract concepts, but essential principles that take place all around us. The following cooking activities included as part of this unit are the perfect medium to introduce and engage all students to the fascinating field of chemistry.
The kitchen, after all, is and has been the quintessential location in the home where food is stored and cooked, but in most cases, it is also the place where food is consumed and the place where family and friends gather to socialize and entertain. Thus, the kitchen is one of the most important places in the home to begin exploring about the wonders of chemistry.
Through inquiry and participation in the activities of this unit, students explore the following essential concepts and skills outlined below.
Essential Concepts
The following are some of the key concepts that this unit explores:
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Chemistry is the study of matter and energy and the interactions between them.
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Chemistry explains what materials are made of and how they combine with one another.
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Micro-organisms in food can be harmful or beneficial.
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A substance that undergoes a physical change is still the same substance after the change (i.e. boiling milk).
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A chemical change produces new substances with properties different than those of the original substances (i.e. adding a culture to milk to produce yogurt).
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Yeast is a living organism belonging to the fungus family.
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Yeast is a live organism that breaths and grows.
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A substrate is the organic material that the microbe uses to get its food from
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Fermentation is a process of growing microorganisms.
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In order for fermentation to take place we must have fungi or bacteria present, no oxygen, and organic matter to act as a substrate.
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Yeasts and molds are fungi. Yeast are unicellular and molds multi cellular.
Essential Skills
Students will be able to:
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Differentiate between a physical and a chemical change.
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Observe, analyze, and record the unique physical and chemical properties of yeast, bacteria, and mold.
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Observe and analyze the fermentation process.
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Create a three-dimensional model of a chemical compound.
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Create a line drawing model of a chemical compound.
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Design and conduct a "valid" experiment.
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Discover chemistry, physics and engineering principles reflected in cooking.
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Identify direct and indirect impacts of chemistry to their lives.
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Describe and illustrate how these chemistry principles work.
Childhood memories
As the aroma from the oven filled the house, a flood of memories overtook my senses, bringing me in time and space to my mother's kitchen in the countryside of the Basque country. The smell of fresh cut vegetables, the cows mooing and lowing accompanied by the sound of the cowbells as the cows are being milked, the cackling of the chickens as they lay their eggs, the greenery of the corn fields surrounded by walnut, hazel nut, and other delicious fruit trees against a backdrop of green mountain tops; these memories speak of a life centered in subsistence; of a way of life centered on the daily work of sowing, caring, and harvesting the fruits of one's labor. This idyllic memory post card speaks of the hard work, and simple way of life centered on the seasons and cycles of earth. These cycles provide both the work and the harvest of earth's richness to be shared around a table.
As part of this childhood memory, I can still sense the weekly kneading and shaping of the dough into loafs as the smell of the yeast dissolved in the lukewarm water and the nutty aroma emanated from the froth that it created as it bubbled and fizzled up to the top. Little did I know that what I was observing was a live organism that breaths and grows. An organism, Saccharomyces cerevisiae, that because of its simple complexity it is now used as a model system. It is thus very appropriate that this unit celebrates and centers on the richness of what life has to offer as a means of exploring chemical principals related to cooking and eating.
From the time that we mix the yeast to the time that the bread comes out of the oven, we can study the multiple physical and chemical changes that take place before, during, and after. This process of explaining the changes that take place to matter belong to the field of chemistry and thus, the process of making bread, pancakes, pizza dough, soda-pop, etc. illustrates these basic principals of chemistry, and serves as a springboard to explore with students what it means to be a chemist.
Given the fact that I want students to be able to observe and analyze these processes, the unit focuses on hands-on activities that can be completed in the classroom. Thus, the unit moves away from baking breads but explores with pancakes and other quick breads (that can be cooked on an electric griddle) the physical and chemical changes that occur as we use microorganisms to assist in the process. This is not to say that we cannot maintain a sourdough starter, which will be fed and regularly observed. As an extension activity, the bread dough can be kneaded and prepared in the classroom and be sent home with a student to be cooked at home.
The success of this unit will be judged not on the content or on the following activities, but by the ability of the teacher to integrate content and context to the background knowledge that the students bring with them to the classroom, and on the ability of the teacher to build upon it. Not only to further engage them in their learning, but also so they are more likely to attach meaning to the new concepts and vocabulary.
Following the analogy of teaching as cooking, the secret in not necessarily in the ingredients, but in how to prepare them; how and when to add the ingredients; how to cook them (medium and time); and how and when to present them at the table. Even then, the job is not complete, because without an appetite, the best meal in the world is not worth the pan where it was cooked.
