standard_description: Calculate the distance between numbers in the complex plane as the modulus of the difference, and the midpoint of a segment as the average of the numbers at its endpoints.
problem_activity: Problem 1
Estimate the mass of the following objects in grams or kilograms, depending on which is more appropriate. Then measure their actual mass using your tool(s).
a.   Pair of scissors
b.   Thumbtack
c.   Ruler
d.   Textbook
Problem 2
What is the mass of each of the following objects, according to the reading on the scale? For any measurement that isn’t exact, make your best estimate.
a.
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b.
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c.
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aligns: no