This is the new updated edition of the first book in the bestselling Uncovering Student Ideas in Science series. Like the first edition of volume 1, this book helps pinpoint what your students know (or think they know) so you can monitor their learning and adjust your teaching accordingly. Loaded with classroom-friendly features you can use immediately, the book includes 25 “probes”—brief, easily administered formative assessments designed to understand your students’ thinking about 60 core science concepts.

Access this probe as a Google form: English

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The purpose of this assessment probe is to elicit students’ ideas about food. The probe is designed to find out if students use a scientific definition of food to distinguish food items from nonfood items.

Justified List

food, nutrients

The best answers are the following: lettuce, sugar, cookies, bread, butter, milk, french fries, candy bar, turkey, pancake syrup, banana, ketchup, and flour. All of these things are scientifically categorized as food. The scientific definition of food is an organic substance containing carbohydrates, proteins, and/or fats that serves as both fuel and building material for an organism. This is often confused by our everyday use of the word food to mean anything that is ingested.

All foods are nutrients but not all nutrients are food. Nutrients are substances that organisms must take in to carry out their life processes. Nutrients include inorganic and organic materials. Although organisms require inorganic nutrients such as water, vitamins, and salt to grow and survive, they are not a source of energy nor are they used as the building material that primarily makes up the body of an organism. Thus, they are not food from a scientific perspective. Food items contain calories, a measure of the chemical energy from carbohydrate, fat, or protein molecules that make up food. Even though some foods, like lettuce, contain minimal calories, they are still considered food.

Although some foods are considered “good” because they provide a rich source of carbohydrates, proteins, and fats (e.g., peanut butter) and others “bad” because they are of limited nutritional value (e.g., candy, cookies), their ability to provide both energy and building material qualifies them as food. Diet soda contains water and inorganic chemicals and thus is not considered food. Furthermore, the label describes diet soda as having zero calories; thus it does not provide energy. Some materials like flour and butter are not consumed directly as food but are used to make food items. However, they are still considered food in a biological sense.

Elementary Students

In the elementary grades, students learn about the needs of organisms, including humans. Through a variety of instructional opportunities, students learn that animals take their food in from the environment by eating plants, animals, or both. They know that all organisms need energy, although energy is still a mysterious concept. Elementary students also learn about food groups and nutrients in the context of human nutrition. They learn the basics of what constitutes good nutrition and how to keep healthy by eating the right foods. This probe is useful in identifying ideas that students have about what makes something “food” before they encounter the more sophisticated ideas about energy flow and matter transformation associated with food.

Middle School Students

In the middle grades, students develop a more sophisticated understanding of food at both a substance and molecular level. Students extend their study of the healthy functioning of the human body and the ways it can be maintained or harmed by diet. This is a time when students can start reading the nutritional labels on food products; paying attention to the carbohydrate, protein, and fat content of foods; learning what a calorie means; and considering what a healthful diet should include.

It is at this time that students can develop a scientific conception of food different from the common, everyday use of the word. Students at this level need to understand that food provides the energy that organisms need to carry out their life processes. They also need to understand that food is broken down into molecules inside the body and that these molecules can be reassembled into the living material of an organism. Students also begin to distinguish substances that are organic in origin from those that are inorganic. This probe is useful in revealing whether students are able to discern the differences between food and other nutrients necessary to carry out life processes.

High School Students

Students at the high school level expand their understanding that food is a source of energy that is released when chemical bonds from carbon-containing molecules are broken during chemical reactions. They are able to distinguish among carbohydrates, fats, and proteins at the molecular level and understand their roles in metabolic processes. They can differentiate between carbon-containing nutrients and inorganic nutrients and can understand their roles in essential cell functions. This probe is useful at the high school level because it can reveal whether students use a common definition of food and whether they understand what food is from a scientific perspective.

Be sure students are familiar with the items on the list. Ask them to cross out any words they are unfamiliar with. Consider having samples of each item to clarify any items students do not recognize. This probe can also be used as a card sort with words or pictures. In small groups, students can sort cards, putting items into three groups—those that represent food, those that do not represent food, and those that they are unsure of—and discussing their reasons for deciding whether each item is considered food. Consider replacing items, or adding additional items, that your students may be more familiar with.

• Students consider food as anything useful taken into an organism’s body, including water and minerals (Driver et al. 1994).
• Elementary students generally know that there are different foods, that there are good foods and bad foods, and that there are different nutritional outcomes such as variations in size and health. In addition, they are aware of certain limits (drinking just water leads to death; eating only one thing—even one good food—is insufficient for good health). They still may believe, however, that food and water have equivalent nutritional consequences, that the height and weight are similarly influenced by amount of food eaten, and that energy and strength result from exercise but not nutrition. These misconceptions tend to fade by middle school (AAAS 1993).
• Students often give a nonfunctional explanation of the importance of food as something needed to keep animals alive, without noting the role of food in metabolism (Driver et al. 1994).
• Elementary students may know that food is related to growing and being strong and healthy but might not be aware of the physiological mechanisms. By middle school, students know that food undergoes a process of transformation in the body (AAAS 1993).
• Some students may think that food “turns into” energy or that it vanishes after it is eaten. Few elementary students know that food is changed in the stomach and, after being broken down into other substances, is carried to tissues throughout the body (Driver et al. 1994).
• After 14-year-old students received instruction about the role of food in metabolism, many reverted to their earlier ideas (Driver et al. 1994).
• High school students regard the term food to mean essential building materials or an energy source but do not always see that both requirements must be met for a substance to be considered food (Driver et al. 1994).
• Most adults are familiar with the names of dietary components such as protein but not with their functions. Many think vitamins provide most of the energy needs, and food is frequently associated with growth rather than energy (Driver et al. 1994).

American Association for the Advancement of Science (AAAS). 2001. Atlas of science literacy. Vol. 1. (See “Flow of Energy in Ecosystems” map, pp. 78–79.) New York: Oxford University Press.

Crowley, J. 2004. Nutritional chemistry. The Science Teacher (Apr.): 49–51.

Farenga, S. J., and D. Ness. 2006. Calories, energy, and the food you eat. Science Scope (Feb.): 50–52.

Robertson, W. 2006. Science 101: How does the human body turn food into useful energy? Science & Children (Mar.): 60–61.

• Take the time to elicit students’ definitions of the word food and use this as the starting point to build an understanding of the word from a biological perspective. Have students identify the difference between the everyday use of the word and the scientific use. Contrasting the two and providing examples may help them see the difference and begin to use the scientific definition, which restricts the term to substances that serve as building materials and a source of fuel for the organism.
• Expand the concept of food to include examples for all kinds of living organisms, including plants. Plants use sugar just as animals do. Unlike animals, plants are able to use the energy from sunlight to transform inorganic carbon dioxide and water, which they take in from their environment, into sugars. These simple carbohydrates serve as building materials and a source of fuel for the plants and so are considered to be their food.
• As middle or high school students’ conception of food develops, introduce, compare, and contrast other commonly used terminology such as nutrient, carbohydrate, fat, protein, vitamin, and mineral. High school students who have a foundation in organic chemistry can consider these terms from a molecular perspective.
• Have students bring in a variety of “good” and “bad” foods. Use the nutrition labels to discuss their value, paying particular attention to their caloric, carbohydrate, fat, and protein content. High school students can examine the kinds of carbohydrates (simple versus complex), fats (saturated, trans), and protein found in the foods.
• Combine this probe with the probe “Is It Food for Plants?” in Volume 2 of this series (Keeley, Eberle, and Tugel 2007).