Hands-on Activity: Cereal Magnets
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Conduct this activity after students have learned about the primary molecules in found food, such as fats, sugars, starches, proteins, etc. It is also helpful if students have a familiarity with magnets (that is, what they are attracted to) since this activity is not an introduction to magnets. However, enough knowledge about magnets can be acquired by students simply playing with magnets at home or by presenting the Two Sides of One Force lesson for an introduction to magnets.
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
To share with the entire class:
Introduction/Motivation (Return to Contents)
As we have just learned, iron is one of the many minerals that is essential to the human diet. Because of iron's importance, chemical food engineers often fortify foods with iron, meaning they add extra iron. One of the foods most commonly fortified with iron is dry breakfast cereal.
In this activity, we will remove the iron that has been added to cereal. In this way, we will be acting as reverse food engineers.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Minerals help your body grow and stay healthy. The body uses minerals to perform several functions. For example, they help build strong bones and teeth, transmit nerve impulses, make hormones and maintain normal heartbeats.
One important mineral is iron. Your entire body needs oxygen to stay healthy and alive. This is because the body needs iron to transport oxygen from your lungs to the rest of your body. Iron helps this process because it is important in the formation of hemoglobin. Hemoglobin is the part of your red blood cells that carries oxygen throughout the body. Several natural foods are iron rich including meat (especially red meat), tuna, salmon, eggs, beans, potato skins and leafy green vegetables.
People who do not get enough iron in their diets tend to become anemic. Anemia is a condition in which not enough red blood cells are present in the blood. The low number of red blood cells results in a lack of hemoglobin, which carries oxygen. If the blood cannot carry enough oxygen to the rest of the body, problems occur. The main symptom of anemia is fatigue. Also, chest pains and shortness of breath can occur. Moreover, people with anemia tend to have pale, pallid skin. Other effects of not getting enough iron include a decreased immunity to disease and sickness. Also, children who lack enough iron in their diets do not develop normally.
While several foods are rich in iron, many people have trouble getting enough in their diets. Thus, chemical food engineers sometimes add iron to processed foods such as cereal. The process used to fortify the cereal is quite simple. The engineers mix powdered iron with the other cereal ingredients. Several types of powdered iron can be used, but the most common types are ferrous sulfate and ferrous fumerate. When ingested, it is converted into iron that can be used by the body in the stomach. The iron mixes with the hydrochloric acid in the stomach to make iron chloride and oxygen gas. The iron chloride is absorbed by the small intestines. The amount of iron added to food is dependent on several factors. For example, the prevalence of iron deficiency in the group of the people who eat the food and the dietary trends of their culture contributes to how much iron is decided to be added to the cereal. Food engineers also add other types of minerals and vitamins to different foods. For example, processed beverages such as orange juice are often fortified with calcium.
Because not everyone eats cereal, food engineers think of ways to deliver essential nutrients to people and kids in some of the world's poorest places. For example, some researchers have developed rice and salts that are fortified with different vitamins and minerals, including iron. This enables children all over the world to receive more nutrients in their diets because rice and salt are consumed in many different cultures.
In this activity, we show that the iron found in processed food is the same type of iron that is attracted to magnets. Students discover this by engineering a process to remove the iron in cereal.
Before the Activity
With the Students
Troubleshooting Tips (Return to Contents)
If students have trouble figuring out how to remove iron from their cereal samples, give them more direction. For example, suggest that the iron may be removed more easily if it is crushed.
One procedure that works well is the following. Begin, by crushing the cereal into small pieces (the smaller the better). Then, put the cereal into a cup of water and stir. Use enough water for the cereal to move freely. Next, place a strong magnet on the outside of the cup and drag it towards the top. Expect to see tiny black specks come up with the magnet, which is the iron that you were looking for.
Alternatively, instead of crushing the cereal and then putting it in water, blend both together. The blender approach works better, however, crushing and stirring into water works as long as the cereal has a high iron content.
If you are not able to get any iron out of the cereal try the following tips. First, try a stronger magnet. The stronger the magnet, the better it will be at removing the iron from the cereal. You can also try crushing the cereal into finer pieces. Also, make sure that the cereal has enough iron in it; use about 100% of the daily recommended serving per cup (note that serving sizes vary).
Investigating Questions (Return to Contents)
Assessment (Return to Contents)
What Does Iron Make You Think Of? Ask students to brainstorm what iron makes them think of. See if they can make the connection between magnets and iron in food.
Changed Foods: Ask students to brainstorm some foods that they have eaten or seen in stores that have extra nutrition added or other components removed, such as fat or gluten).
Activity Embedded Assessment
Iron Removal Plan: After the activity is introduced, ask students to write quick plans to get the iron out of the cereal samples. Ask them to explain why they chose their methods. Examine and approve their plans before they begin work.
Guide to Iron Removal: Ask students to write or draw the steps of the process they used to remove the iron from the cereal. Tell students to imagine they are food engineers making a laboratory manual for other researchers to follow.
Removing Other Minerals: Ask students to think about other foods from which they could remove iron or other minerals. Ask them to make another plan for this process.
Activity Extensions (Return to Contents)
Have students test the iron content of a variety of different cereals. To do this, they repeat the activity procedure with different samples.
Activity Scaling (Return to Contents)
References (Return to Contents)
Dietary Supplement Fact Sheet: Iron. Updated July 26, 2005. Office of Dietary Supplements. National Institute of Health. Accessed April 26, 2007. http://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
Minerals. Reviewed August 2004. Kids Health. Nemours Foundation. Accessed April 26, 2007. http://www.kidshealth.org/kid/stay_healthy/food/minerals.html
Matsui MD, William. MedlinePlus Medical Encyclopedia: Anemia. 2005. A.D.A.M., Inc. Accessed April 26, 2007. http://www.nlm.nih.gov/medlineplus/ency/article/000560.htm
Guidelines for Iron Fortification of Cereal Food Staples. May 2001. Sustain: Sharing U.S. Technology to Aid in the Improvement of Nutrition. Accessed April 26, 2007. http://www.sustaintech.org/technology/iron.htm
Copyright© 2013 by Regents of the University of Colorado; original © 2007 Duke University
Supporting Program (Return to Contents)Engineering K-PhD Program, Pratt School of Engineering, Duke University
Acknowledgements (Return to Contents)
This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.