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Contributed by: Council of Chief State School Officers (CCSSO/SCASS)
Description:Students are given three unknown samples (A, B, and C) and perform two chemical tests to determine whether these unknowns contain protein and/or starch. The reagents they will be using will cause discoloration and are corrosive or toxic and, therefore, require careful handling. Tap water will serve as a control for the experiment.This task is designed to take students approximately 40 to 50 minutes to complete.
Overall Task Content Area:
Specific Knowledge Areas:
Performance Expectations:
National Science Education Standards:12 F SPSP 1: Personal and community health: Grades 9-121.5 Selection of foods and eating patterns determine nutritional balance. Nutritional balance has a direct effect on growth and development and personal well-being. Personal and social factors - such as habits, family income, ethnic heritage, body size, advertising, and peer pressure - influence nutritional choices. 12 A SI 1: Ability to do scientific inquiry: Grades
9-12 1.4 Formulate and revise scientific explanations and models using logic and evidence. Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation. (Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)
General Instructions to the Teacher:This task is designed to take students approximately 40-50 minutes to complete.Students will be working in groups of 4-6 for the experiment/activity part of this exercise. Students work together for up to 20 minutes. They should be instructed to notify you when finished with the group work, and then to go on to the individual work beginning with question #1. If students are still working together 20 minutes after the testing begins, instruct them to cease their group work and begin individual work. At this point, they may no longer talk. Whether or not they are just beginning their individual work, remind students that they now have about 25 minutes to complete the individual activity. Students should be ready to work as soon as the period begins. Group assignments should be made in advance. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be accessible. All supplies should be clearly labeled.
Materials for The Nutritional Content of Food:At this station students should have:
Advance Preparation:Each group will need 8 medicine cups, 8 stirrers, and 5 pairs of plastic gloves. All groups will share the dropper bottles of reagents. We ask that you make up the powdered milk solution and the Kool-aid (labeled A and B, respectively) as the two other unknowns. Students will be using color changes to determine the presence or absence of specific nutrients. As you mix the powdered milk, add enough water to make a minimum of 200 mL. In addition, the powdered milk solution should be diluted enough that color changes can be seen. We recommend no more than one gram of powdered milk per 100 mL of water. Please label this sample as "Unknown A." For the Kool-aid, add about 0.25 grams per 100 mL of water. Please label this sample as "Unknown B."
Safety:
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