Level 3: Use a chance device to represent a source of variability or the total variability of the system.
3A
Use chance devices to represent variability
Student constructs a spinner simulation by allocating sectors of a spinner or balls in an urn in proportion to observed values.
"I am flipping a coin to show the chances that a person might prefer Coke or Pepsi, just by chance."
"I think small mistakes are more likely than big mistakes, so the largest areas of the spinner represent small errors. And the smaller portions of the spinner represent large mistakes. So, when you spin, you are more likely to get a small mistake than a large one."