Reflection: Checks for Understanding What Is A Mole? - Section 5: Whole Group Discussion


Most of my students thought it was odd making up a new counting unit based on counting a seemingly random bag of items.  But once they started, many of them were actually quite adamant that their counting unit should become a standard unit of measurement.  They all agreed that the amount of time it took to count them was way too long, and that they had way too many items to count (as one group indicated by naming their units "waste of time"), which led my students to a better understanding that the mole is really representative of a very large number.  

Incidentally, there were four different students who asked me if they could just weigh the particles instead of counting them, which indicated to me that those students will grasp the grams to moles idea readily.  (I didn't let them use a balance--all balances were conveniently put away, but I applauded their efforts in finding a short cut!)

Samples of student work are included below:

The calculations portion of the assignment will vary depending on how many particles each group count, however, the last question asks "How does your new unit compare to the mole?" which could yield similar results.  I was looking for answers that explain how a mole is much larger than the student-created units and answers that both units are representative of numbers larger than one would want to count.

This student above referred to a mole and their created unit of banana as both counting units, which is part of what I was looking for.  The student below had a similar answer.  This answer is indicative of how most of my students answered the question.  I wanted a deeper answer and may need to craft a follow-up question to add in order to get my students to the answer I want.

The following student did recognize that the mole is much larger than his created unit.

This student's response is more detailed in describing the mole compared to his created unit.


  Student Work
  Checks for Understanding: Student Work
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What Is A Mole?

Unit 3: Chemical Reactions and Stoichiometry
Lesson 7 of 14

Objective: SWBAT explain what a "mole" is and that it is based on carbon's atomic mass.

Big Idea: A mole is a unit of measurement equal to 6.02 x 10^23; The mole is equal to the number of atoms of carbon-12 needed to make 12 grams.

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