CTS Section IV Research Summary pp 100-101 — SCIENCE CURRICULUM TOPIC STUDY (CTS)

CTS Guide: Energy Extraction, Food, and Nutrition pp 100-101- Section IV Research Summaries

Concept of Food

Driver et al. (1993): The word “food” has a different meaning to students in everyday life than in the way it is used in biological processes. Students tend to think of food as anything taken into an organism including water, minerals, and in the case of plants- carbon dioxide and even sunlight. Students often give a non-functional explanation of why food is needed without reference to its role in metabolism, growth, or repair. Secondary students often fail to connect food to respiration, even after taking a biology course. Secondary 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. Misunderstandings are further confounded when students think the purpose for food in plants is different than the purpose for food in animals.
Barker (1985): In a large sample of students ages 8-17 and teachers, the concept of food was found to be fluid and context dependent on who is considered the eater and whether materials are separate or in combination.
Roth, Smith, and Anderson (1983): Understanding that the food plants make is very different from other nutrients, such as water and minerals, may be a prerequisite for understanding the idea that plants make their food rather than acquire it from the environment.

Dietary Components

Lucas (1987): In a survey of 1033 adults, even though they were familiar with the names of dietary components, many did not know their function. 37% thought proteins and 19% thought vitamins provided most of the energy a body needs. A large number selected proteins as the product of photosynthesis.
Arnold and Simpson (1982): Found that over 30% of 11-13-year-olds thought a carbohydrate is a gas.

Good Nutrition

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 2009).

What Happens to Food in the Body

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 2009).
Cakici and Yilmaz (2005): Some children describe digestion as melting or dissolving food and that while food is broken down, its chemical composition remains unchanged. Up through age 7 children believed the food they ate stayed in their bodies. By age 10, they thought part of it stayed and part of it left the body.
Texeira (2000): Students may misunderstand how food is used for growth. In a study of elementary students, the children thought food leaves the stomach and moves into the legs and arms, where it accumulates and makes them grow bigger.
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. 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).

Food for Plants

Before using computer simulations, some students thought that water is the source of energy for plants (Çepni, Tas, and Köse
2006).
In a study by Tamir (1989), some students thought sunlight, associated with energy, was the food for plants. Many students
also considered minerals taken in from the soil as food or believed that minerals had a direct role in photosynthesis.
Understanding that the food plants make is very different from other nutrients, such as water and minerals, may be a prerequisite for understanding the idea that plants make their food rather than acquire it from the environment (Roth, Smith, and Anderson 1983).
In Wandersee’s study (1983) of 1,405 students ages 10–19, many thought that the soil in a plant pot would lose weight as the plant grows because the plant uses the soil for food.

Getting Energy from Food

Driver et al. (1994): Several studies show that students do not recognize that plants respire and when they do, they often fail to perceive it as the energy conversion process. Many thought photosynthesis is the process that releases energy in plants. Some students think food turns into energy or that it vanishes after it is eaten.
Leach et al (1992): Students recognize oxygen is needed to live but few students associated release of energy from food in connection with the need for oxygen. Few understood the role of breathing and saw the process as an end in itself.
Gayford (1986): In a sample of advanced biology students, 79% did not consider respiration as involving energy conversions. They thought respiration forms energy which is used in synthesis reactions. 74% viewed ATP as having high energy bonds which release energy- a view probably arising from teaching.
Simpson (1984): It is common for students to believe that digestion (rather than cellular respiration) is the process that releases useful energy from food. This idea may come from students incorrectly linking two ideas – the idea that digestion breaks down food, and that organisms get energy from food.