Curricular Unit: Students As Scientists
Contributed by: Engineering K-Ph.D. Program, Pratt School of Engineering, Duke University
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It doesn't require rocket science - kids can learn how to do scientific inquiry with materials as ordinary as pennies and bubble gum. click for copyright |
Grade: 7 (6-9)
Time Required: 6 hours Spread over 2-3 weeks
Summary
This curricular unit contains two lessons that let students actually do the work of scientists as they design their own experiments to answer questions they generate. In the first lesson and its associated activity, students conduct a simple test to determine how many drops of each of three liquids can be placed on a penny before spilling over. The three liquids are water, rubbing alcohol, and vegetable oil; because of their different surface tensions, more water can be piled on top of a penny than either of the other two liquids. However, this is not the main point of the activity. Instead, students are asked to come up with an explanation for their observations about the different amounts of liquids a penny can hold. In other words, they are asked to make hypotheses that explain their observations, and because middle school students are not likely to have prior knowledge of the property of surface tension, their hypotheses are not likely to include this idea. Then, they are asked to come up with ways to test their hypotheses, although they do not need to actually conduct these tests. The important points for students to realize are that 1) the tests they devise must fit their hypotheses, and 2) the hypotheses they come up with must be testable in order to be useful. In the second lesson, students chew bubble gum until it loses its flavor, and after allowing the chewed gum to dry for several days, they determine the amount of mass lost. From the mass lost, they calculate the percentage of sugar that was in the gum originally. This teacher-led activity causes students to generate new questions about the varieties of chewing gums and their ingredients, and it also points out the need for controls. Students then design and execute new, controlled experiments based on their own questions. When students ask their own questions and devise ways to answer them scientifically, they begin to truly understand and appreciate the scientific method.
Engineering Connection |
Keywords: hypothesis, variables, controls, experimental design, surface tension, bubble gum, sugar
Related Subject Areas
Related Lessons
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Assessment (Return to Contents)
- Describe a simple experiment and ask students to state a hypothesis that could be tested by the experiment. An example of such an experiment could be that a student tested the effects of adding fertilizer to the soil of a bean plant grown in a flowerpot. (A suitable hypothesis would be, "Adding fertilizer causes the plant to grow taller than it would without the addition of fertilizer.) Then ask students to describe a test of the hypothesis. (Growing two plants under identical conditions, one with fertilizer added and one without, would be an appropriate test of the hypothesis.)
- In a written assignment, ask students to explain why a control should have been used in the initial gum experiment.
- In a written assignment, ask students to describe an experiment to determine whether sugarless gum loses as much mass after chewing as regular gum does.
Contributors
Mary R. Hebrank, Project Writer and Consultant, Duke UniversityCopyright
© 2004 by Engineering K-Ph.D. Program, Pratt School of Engineering, Duke Universityincluding copyrighted works from other educational institutions and/or U.S. government agencies; all rights reserved.
Supporting Program
Engineering K-Ph.D. Program, Pratt School of Engineering, Duke UniversityLast Modified: February 6, 2007