Many of the experiments that led 20th century scientists to discover the nature of the atom involved indirect observation and inference. During the early 1900s, scientists such as J. J. Thomson and Ernest Rutherford were faced with the challenge to develop an accurate mental picture of the atom—an object much too small to be directly observed. Every year many students faithfully study schematic diagrams of Rutherford's "Gold Foil Experiment" without ever experiencing the thinking that led those scientists to their revolutionary conclusions. In this demonstration, students are asked to form a mental picture of an object hidden beneath a cardboard blind. Students must formulate hypotheses about the size, shape, and composition of the object while watching you probe the object with a laser beam. Students are actively engaged throughout this demonstration exercise about indirect observation as they develop a deeper understanding of how scientists such as Rutherford “knew without seeing.”
Kit includes valuable Teacher Notes with helpful teaching tips, reproducible student worksheets and enough reusable materials to perform the demonstration an unlimited number of times.
Concepts: Indirect measurement, atomic structure, inference.
Time required: 20 minutes
Materials provided: Cardboard square, blotting paper, mirrors, laser pointer, 8-foot plastic band.
Additional ResourcesNo Additional Resources at the time.
Flinn Catalog/Reference Manual Page 348
Flinn Middle School Catalog/Reference Manual Page 272
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