TE Activity: Cereal Magnets

Transcription

1 TE Activity: Cereal Magnets Summary In this activity, students will design a process that removes the most iron from the cereal. This activity is meant for the students to experiment with different materials using what they know about iron, magnets, and forces to design the best process for removing the iron from the cereal. Engineering Connection The students will act as "reverse" food engineers by designing a process to remove the iron from fortified cereal. Food engineers often add certain vitamins and minerals to food in order to make them healthier. Contents 1. Pre-Req Knowledge 2. Learning Objectives 3. Materials 4. Introduction/Motivation 5. Vocabulary 6. Procedure 7. Troubleshooting Tips 8. Troubleshooting Tips 9. Assessment 10. Extensions 11. Activity Scaling 12. References Grade Level: 4 (3-5) Group Size: 3 Time Required: 1 hours including lesson. Expendable Cost Per Group US$ 2 Keywords: food, minerals, iron, nutrition Related Curriculum Activity Dependency Fortified Breakfast subject areas Science and Technology Biology lessons Fortified Breakfast Educational Standards North Carolina Science 4.03 Discuss how foods provide both energy and nutrients for living organisms. (Grade 4) [2004] 4.05 Determine that foods are made up of a variety of components (Grade 4) [2004] Pre-Req Knowledge (Return to Contents) This lesson should be taught after you have already taught about the main molecules in food (fats, sugars, starches, proteins, etc.). It would also be helpful if the students already have a familiarity with magnets (i.e., what they are attracted to). However, enough knowledge about magnets can be acquired by students simply playing with magnets at home. This lesson is not an introduction to magnets. Such an introduction 1/6

2 is available on TeachEngineering in the lesson "Two Sides of One Force". Learning Objectives (Return to Contents) After this activity, students should be able to: State that minerals are an important part of our diet. Know that different minerals have different rolls in our health and state some of them. Describe why iron is an important part of our diet. List several foods that contain iron. Describe why food engineers add iron and other minerals to cereal. State that the iron in our cereal is the same iron that is attracted to magnets. Materials List (Return to Contents) Each group needs: 480 ml (1 cup) of cereal with a high iron content (e.g., Total or any cereal that contains 100% of the recommended daily allowance of iron). To share with the entire class: Magnets of varying strengths (Magnets generally used in the classroom will work. Refrigerator magnets have less strength and may not work, but will provide the students with an alternative with which to experiment.) Ziploc bags Cups of water Blender Electronic balance. The balance must be sensitive enough to be able to detect small changes in weight (at least one tenth of a gram). If this is not available to you there are alternative ways to quantify the amount of cereal removed (see procedure). Introduction/Motivation (Return to Contents) As we have just learned, iron is one of the many minerals that are essential to our diet. Because of iron's importance, food engineers often fortify foods with iron, meaning they add extra iron. One of the foods most commonly fortified with iron is 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) Mineral: Natural compounds that are important in helping the body perform many vital functions. Iron: Mineral that is necessary to transport oxygen around the body (part of hemoglobin). Calcium: Mineral that is helpful in building strong bones. Potassium: Mineral that helps to keep muscles and nervous system working properly. Zinc: Mineral that helps your immune system. Fortify: To add one or more ingredients to a food to increase its nutritional content. Magnet: An object or device that produces a magnetic field which attracts other magnets and certain metals. Procedure (Return to Contents) Background 2/6

3 Minerals help your body grow and stay healthy. The body uses minerals to perform several functions. For example, they help you build strong bones, transmit nerve impulses, make hormones, and maintain a normal heartbeat. 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's important in the formation of hemoglobin. Hemoglobin is the part of your red blood cells that carries oxygen throughout the body. There are several foods that 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 diet tend to become anemic. Anemia is a condition where there is not enough red blood cells in the blood. Due to the lack of red blood cells, there is also a lack of hemoglobin, which as mentioned previously carries oxygen. If the blood cannot carry enough oxygen to the rest of the body, problems will 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. Also, children who lack enough iron in their diet do not develop normally. While there are several foods that are rich in iron, many people have trouble getting enough in their diet. Therefore, food engineers often add iron to foods such as cereal. The process used to fortify the cereal is quite simple. The food engineers simply 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 your stomach. The iron mixes with the hydrochloric acid in your stomach to make iron chloride and oxygen gas. The iron chloride is absorbed by your 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 will eat the food and the dietary trends of their culture contribute to how much iron should be added to cereal. Food engineers also add other types of minerals and vitamins to different foods. For example, orange juice is often fortified with calcium. Because not everyone eats cereal, food engineers are thinking of ways to deliver essential nutrients to people and kids in some of the world's poorest places. For example, some scientists and engineers have developed rice and salts that are fortified with different vitamins and minerals, including iron. This allows children all over the world to receive more nutrients in their diet because rice and salt are consumed in many different cultures. In this activity, we will show that the iron found in food is the same type of iron that is attracted to magnets. The student will discover this by engineering a process to remove the iron in cereal. Before the Activity Obtain the materials. Divide the materials so that each group has a set. With the Students 1. Ask the students if they have ever read the nutrition label on their foods. Also, ask them if they ever noticed things such as iron or calcium on the label. 2. Define what a mineral is and discuss some of the important minerals. Have the students write down the functions of the minerals defined above and brainstorm as a class what might happen if you did not get enough of the mineral. 3. Tell the students that iron are oftentimes added to cereal. Tell the students that they are going to 3/6

4 design a process to remove the iron from cereal. Inform them that engineers often do the opposite. 4. Divide the class into groups of two or three students each. Groups can be larger or smaller depending on size of class and availability of materials. 5. Pass out cereal to each group and let them examine it. Have them notice that they cannot see the iron at this point. 6. Allow the groups 5-10 minutes to discuss their plan to extract the iron from the cereal. Walk around to see if their plans make sense. Don't tell them that their plans are wrong or will not work yet. 7. Have the groups gather the materials that they chose. 8. Give the students about minutes to try to extract the iron from their cereal. During this time, walk around the room and talk to the groups about what they are doing. Make suggestions for changes if their process is not working. a. First, give small hints such as, "think about what you could do with the water." b. Second, explain what the different materials will do and how it may help them. For example, tell them that the water helps separate the iron from the cereal and allows it to move. c. If none of these works, begin giving more direct directions. 9. Ask the students to weigh how much iron they can remove from their iron. In order to be able to weigh the iron, first weigh a clean tissue. Then, wipe the iron off of the magnet. Keep the tissue as dry as possible. If the tissue does get wet, allow it to dry and then weigh it again. The weight of the tissue with the iron minus the weight of the clean tissue is the weight of the iron. Note: If a sensitive scale is not available you can have the students count how many specks of iron they can remove from the cereal. This process is not as accurate. However, it will give the students an idea of how much iron is removed from the cereal which is most important. 10. If time allows, give the students more time to revise their process and trade in their previous materials for new materials. Troubleshooting Tips (Return to Contents) If the students are having trouble figuring out how to remove the iron from their cereal, 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. There should be 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. You should see tiny black specks come up with the magnet. This is the iron that you were looking for. Alternatively, instead of crushing the cereal and then putting it in water, you could blend both together. The blender will work better. However, crushing and stirring into water should work as long as you are using a cereal with 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 your cereal has enough iron in it. About 100% of your daily serving per cup (remember that serving sizes vary) should work. Investigating Questions (Return to Contents) What procedures worked best when you tried to remove the iron from the cereal? Why do you think the blender helped you get iron out of the cereal? How do you think the extra iron was added to cereals? 4/6

5 Why do you think certain cereals are fortified with extra iron? Assessment (Return to Contents) Pre-Activity Assessment What Does Iron Make You Think Of?: Ask the students to brainstorm what iron makes them think of. See if they can make the connection between magnets and iron in food. Changed Food: Ask the students to brainstorm some foods that they have eaten or seen that have extra nutrition added (or harmful things, such as fat, removed). Activity Embedded Assessment Iron Removal Plan: After the lesson is introduced, ask the students to write a quick plan to get the iron out of the cereal. Ask them to explain why they chose their method. You should look at their plan before they begin work. Post-Activity Assessment Guide to Iron Removal: Ask the students to write or draw the steps of the process they used to remove the iron from the cereal. The students can act as if they are food engineers making a manual for other people. Removing Other Minerals: Ask the students to think about other foods they could remove iron or another mineral from. Ask them to make another plan for this process. Activity Extensions (Return to Contents) There are several ways to extend this activity depending on how you want to take the class. One way to extend the lesson is by having the students test the iron content of different cereals. The procedure to do this would be the same as in the activity repeated three times. Activity Scaling (Return to Contents) For lower grades, give the students more direction on the iron removal. For example, give the students the specific materials that they will use (i.e., magnet, water, cup, plastic bag for crushing). For upper grades, give the students less direction or allow them to choose different foods to remove iron from. For example, you could simply ask the students to remove the iron from a food. Then, you could give them time to think about what would work on their own and request certain materials (or bring them in). References (Return to Contents) Dietary Supplement Fact Sheet: Iron. Updated July 26, Office of Dietary Supplements. National Institute of Health. Accessed April 26, Minerals. Reviewed August Kids Health. Nemours Foundation. Accessed April 26, Matsui MD, William. MedlinePlus Medical Encyclopedia: Anemia A.D.A.M., Inc. Accessed April 26, /6

6 Guidelines for Iron Fortification of Cereal Food Staples. May Sustain: Sharing United States Technology to Aid in the Improvement of Nutrition. Accessed April 26, Owner (Return to Contents) Engineering K-Ph.D. Program, Pratt School of Engineering, Duke University Contributors Liz Harper Copyright 2007 by Engineering K-Ph.D. Program, Pratt School of Engineering, Duke University including copyrighted works from other educational institutions and/or U.S. government agencies; all rights reserved. Last Modified: February 12, /6