NSF Research Experiences for Teachers NSF RET INDIRECT OBSERVATION: HOW TO SEE WHAT WE CAN T SEE? LESSON ACTIVITIES TAVARES ARMSTRONG.

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1 NSF Research Experiences for Teachers RET NSF TAVARES ARMSTRONG INDIRECT OBSERVATION: HOW TO SEE WHAT WE CAN T SEE? Subject Chemistry Grade Levels Essential Question Science Objectives Math Objectives What are the strengths and limitations of analogies, metaphors and scientific models? What are the strengths and limitations of the current atomic model? Determine indirect measurement of figures using scale drawings. LESSON ACTIVITIES Engage Explore Explain Elaborate Evaluate Determine the pattern inside the Ob-Scertainer with out opening it. Determine the size, shape, and composition of an unknown object using indirect observations... The use of indirect observations is just as important as direct observation. Many models of scientific phenomena and principles are described by models. There are materials which are too small to see. There phenomena too large to bring into the class room. Therefore the need to have a visible representation of these materials, or events is necessary. The early scientist used indirect observation to explain one such concept, the atom. Over the course of time and as technology developed the model of the atom has evolved. During the lab we stepped into the footsteps of the early scientist. We use the known technology of the time and indirect observations to help us develop a model of something we can not see. From gold foil to gold nanorods, the process of indirect observations is still employed today. We have come along way since Rutherford s experiment leading to the orbital view of the atom. However the basic idea behind the technique employed is widely used today. Current instrumentation used in cutting edge research still relies on indirect observation. Scanning electron microscopes, transmission electron microscopes, and scanning tunneling microscopes, have allowed us to image down to the atomic level. These images allow us to see what we historically could not see. Informal evaluation of the process used to determine the shape, size and composition of the unknown object. Formal assessment of the conclusion drawn based on the observations

2 recorded. Summary of how the lab represents the early experiments which led to the formation of the atomic model. Materials Ob-Scertainer tm Blotting paper 12 x 19,6 * Cardboard square 17 x 17 Laser pointer* Mirror, Plexiglas, 21/2 x 31/2, 3* Marker Plastic Strip, 4 x 88 * Binder or jumbo paper clips (4) transparent tape *= materials included in Indirect Observation and Inference Kit Flinn Scientific Ap7425 Ob-Sertainer tm available through LAB-aids cat.no. 100 Assessment Products Each student will be required to submit their drawing of the geometric shape located inside of their Ob-Scertainer. Along with the drawing a brief description as to why they modified their drawing between the first and second drawing. Finally a comparison of their drawing with the actual geometric shape. Summary of group discussion to the experience of identifying the unknown objects. Summary should include the answer to the following questions: 1. What worked well? 2. What obstacles did the group encounter? 3. What material or equipment would have made the identification easier? 4. How does the lab relate to the development of the atomic model? INFORMATION FOR TEACHERS Standards Chemistry TEKS (1) Scientific processes. The student, for at least 40% of instructional time, conducts laboratory and field investigations using safe, environmentally appropriate, and ethical practices. The student is expected to: (A) demonstrate safe practices during laboratory and field investigations, including the appropriate use of safety showers, eyewash fountains, safety goggles, and fire extinguishers; (2) Scientific processes. The student uses scientific methods to solve investigative questions. The student is expected to: (A) know the definition of science and understand that it has limitations, as specified in subsection (b)(2) of this section; (B) know that scientific hypotheses are tentative and testable statements that must be capable of being supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories; (E) plan and implement investigative procedures, including asking questions, formulating testable hypotheses, and selecting equipment and technology, including graphing calculators, computers and probes, sufficient scientific glassware such as beakers, Erlenmeyer flasks, pipettes, graduated cylinders, volumetric flasks, safety goggles, and burettes, electronic balances, and an adequate supply of consumable chemicals;

3 (F) collect data and make measurements with accuracy and precision; (H) organize, analyze, evaluate, make inferences, and predict trends from data; and (I) communicate valid conclusions supported by the data through methods such as lab reports, labeled drawings, graphs, journals, summaries, oral reports, and technology-based reports. (3) Scientific processes. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to: (A) in all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student; (F) research and describe the history of chemistry and contributions of scientists (6) Science concepts. The student knows and understands the historical development of atomic theory. The student is expected to: (A) understand the experimental design and conclusions used in the development of modern atomic theory, including Dalton's Postulates, Thomson's discovery of electron properties, Rutherford's nuclear atom, and Bohr's nuclear atom; Texas College Readiness Standards Science Foundation Skills IV. VIII. Science, Technology and Society A. Interactions between innovations and science 1. Recognize how the scientific discoveries are connected to technological innovations. C. History of Science Chemistry 1. Understand the historical development of major theories in science 2. Recognize the role of people in important contributions to scientific knowledge B. Atomic Structure 1. Summarize the development of atomic theory. Understand that models of the atom are used to help understand the properties of elements and compounds Prior Student Learning Students should have a basic understanding of measurement and unit conversion in the metric system and expressing numbers in scientific notation. Possible Prior It is not possible to measure the size of something if you don t have a ruler with appropriate size graduations

4 Misconceptions Students have a hard time believing atoms are mostly empty space. Students think that the atom actually look like the scientific models. Lesson Sequence Background Information The lesson is design to be taught at the beginning of the Atomic Theory Unit. In chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity. It began as a philosophical concept in ancient Greece (Democritus) and India and entered the scientific mainstream in the early 19th century when discoveries in the field of chemistry showed that matter did indeed behave as if it were made up of particles. The word "atom" (from the ancient Greek adjective atomos, 'indivisible' ] ) was applied to the basic particle that constituted a chemical element, because the chemists of the era believed that these were the fundamental particles of matter. However, around the turn of the 20th century, through various experiments with electromagnetism and radioactivity, physicists discovered that the so-called "indivisible atom" was divisible. Adaptations for Special Learners Extensions Remove the cardboard blind and allow the students to see the unknown object. Allow the students to explain what is happening to the laser as it hit s the object. Help the students make the connection to Rutherford s Gold foil experiment. Provide each student with images from different microscopy techniques to show the range and power of indirect observation. Have the students research current techniques used in modern research.

5 Engage (10-15 mins) Obsertainer Using accurate observations and checking the accuracy of a hypothesis (scientific method) SAME

6 Explore Explore