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Case Studies in Science Education

Linda — Grades 2-4

Name Linda
Experience 15 years as a classroom teacher; first year in the position as science specialist
Grade & Subject K-4 science
Classroom Urban elementary school
Demographics Visits all K-4 classrooms in school; total of more than 600 students
Curriculum Specified by the district

Contents




Module 1 -- Introducing the Case

In her position as science specialist, Linda is responsible for both direct instruction in science through regular visits to each of 26 classrooms, as well as ongoing support of classroom teachers in their own science teaching and learning. One of her primary concerns is how to deal effectively with students' ideas, specifically, how to facilitate scientific understandings through higher order thinking skills and designing fair experiments.

While working with a second-grade class, Linda challenges her students to explain why a dropper enclosed in a bottle of water rises and falls as students squeeze and release the sides of the bottle. With this activity, Linda realizes that it can be difficult to move students from their own, sometimes scientifically inaccurate, understandings to those that are more scientifically accurate. After groups of fourth-grade students gather materials and try to design fair experiments to answer a question about which surfaces snails "prefer" to move on, Linda begins to explore better ways in which she can help students design experiments in order to construct scientific ideas from hands-on activities.



Cartesian Diver Activity

Students are given bottles filled with water and an eyedropper. Groups are asked to squeeze and release the bottle, making the eyedropper, or "diver," rise and fall. Groups then discuss with one another and with Linda what makes the eyedropper move.



Snail Experiment

Students design experiments to answer the question "What do land snails like to walk on?" Sand, water, sawdust, aluminum foil, and waxed paper are offered as surfaces for students to use when designing their experiments and carrying them out with land snails.




Discussion Questions

What aspects of the Cartesian Diver activity would seem most likely to contribute to the development of scientifically accurate ideas? Scientifically inaccurate ideas? What aspects of the Snail experiment?















If one goal of science teaching and learning is to help students build scientifically accurate ideas, then what do you think must be taken into account when designing and implementing science activities?















If one of your goals were to help students learn what it means to design a "fair" experiment, then how would you address this goal?




















Module 2 -- Trying New Ideas

Linda meets periodically with Anita Greenwood, a science educator at the University of Massachusetts in Lowell and a professional development consultant for Linda's district. Together they elucidate some of the ways that teachers can design activities that reduce the possibility that students will build non-scientific ideas. This includes refining the approach to science experiments to ensure that they are "fair" that is, that they produce scientifically valid data.

In a fourth-grade class, Linda works with the classroom teacher, Jean, to design and troubleshoot an experiment that will help students understand that machines make work easier. Although students record their data, the unit of measurement for recording the results, as well as the direction of the numbers from top to bottom on the scales constructed by students, varied among groups.

Jean and Linda decide that one way to help students build more accurate understandings is to focus on controlling more variables. When repeating the experiment, both teachers want students to understand why such factors as too many variables or an inferior apparatus can interfere with building scientifically accurate understandings.



Inclined Plane Experiment

Students test how effort, which to them represents work, is affected by the use of an inclined plane. After hanging weights in a plastic bag that moves along a scale on a piece of cardboard, students pull the apparatus up an inclined plane, record their data, and try to determine if simple machines reduce effort.



Discussion Questions

How would you critique the Inclined Plane activity with regard to helping students build scientifically accurate ideas? Scientific ways of finding answers to questions?















What are the strengths and weaknesses of activities that focus primarily on having students find "the right answers?" Those that focus primarily on having students learn and practice scientific process skills?

















In your opinion, what would be the appropriate course of action when students hold scientifically inaccurate ideas after doing a science activity?


















Module 3 -- Reflecting and Building on Change

Knowing that too many variables in an experiment can contribute to its not being considered fair in a scientific sense, Linda has refined her ideas about the experiments her students will design and conduct.

She and her students have seen in previous experiments how the number of variables, distracters such as sandwich bags covering a scale, and inconsistent units of measurement for recording data all interfered with fairness, as well as the ability to pool, compare, and make sense of data.

Linda challenges fourth-grade students to design a round of experiments to determine whether mealworms prefer a light or dark environment. By frequent return to the central question, Linda believes that students will be helped to design a fair experiment. Also, students present their designs to the whole class and invite feedback, especially that pertaining to variables. Linda is encouraged by the caliber of the students' feedback to one another and looks forward to building upon what she and her students have learned about designing experiments with other classes.



Mealworm Experiment

Groups of students use flashlights, cardboard tubes, straws, and other materials to design experiments that will help answer questions about the environment preferred by mealworms. Each group presents its design to the whole class and invites feedback about its fairness. Groups consider the feedback and revise their designs accordingly before actually conducting the experiment.



Discussion Questions

What do you consider to be the most significant differences between the Snail experiment and the Mealworm experiment? The Inclined Plane activity?















What do you consider to be the appropriate balance between activities designed to focus on specific science understandings and those designed to build an understanding of scientific methods of investigation?















What aspects of Linda's case study do you find to be most useful in our own science teaching and learning situation? Least useful? Why?

















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