Objectives
The first objective of the unit is for students to be able to know an objects size as it compares to a known reference point. Students should recognize that an objects size is measureable by means of a scale or reference point. Students must also be able to arrange objects in order based on their size. Students need to be able to describe an object in multiple contexts. 4 Students must understand some objects are too tiny to view with the naked eye, which include micro, nano, molecular, and atomic size objects. These tiny divisions define different systems in the microscopic world. Many students have the misconception that objects in the microscopic world are the same size. Very often, their frame of reference for a tiny object relates to what they perceive as tiny. They may think an ant is very tiny and perceive that it is on the same scale as a cell or an atom, when in actuality all three of these objects are dramatically different in size. Another objective of the unit is to help students understand size can be comparisons between two known objects or an actual numeric measurement. Students will need to know the differences in value between 10, 100, 1000, and 1,000,000 and their inverses. 5 They need to understand the metric prefixes of kilo, centi, milli, micro, and nano and their relationship to each other.
A second set of objectives relate to properties of matter. Students should have an understanding of bulk materials and their properties. Students need to be aware that properties change at the nanoscale because of quantum mechanics. Students need to understand that some properties of nanoparticles are due to surface area. Students should be able to explain why properties of nanoscale objects can be different from larger particles of the same material at the macro scale. Finally, students need to understand the link between surface area, size of particles, and reactivity.
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