What is a Weighted Average?

Have you ever wondered why the atomic mass listed on the periodic table isn't a whole number? This video explains how weighted averages are calculated and relates the average to the relative atomic mass. Viewers are then given an element and isotopes and asked to predict the weighted average. 

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CCSS: Adaptable
Instructional Ideas

  • Create your own examples of elements with isotopes, such as Barium and Xenon, so class members can interpret the weighted atomic mass 
Classroom Considerations

  • Requires prior knowledge of the parts of an element and isotopes
  • Ideally, this video comes after scholars understand the periodic table and its organization
  • Video is the third in a series of 29
Pros

  • Utilizes a graphic of a scale that most viewers will understand
  • Teaches the topic from more than one perspective to allow for greater understanding
Cons

  • None
Common Core