Making Precise Measurements Vocabulary: scale meniscus precision “The Pantheon”, architect: Apollodorus of Damascus, 125 CE

Standardization Scientists need to measure as accurately as possible with the device they are using. Standard practice is to estimate between the lines of the smallest increment on a measuring device. This estimated digit represents the precision of the devise. (This is a second definition of precision.)

Accurate measurements What is the volume in the graduated cylinder? Things to think about: What direction is the scale? (Up or down in this case?) What is the scale? (What is the increment between the lines?)

Accurate measurements What is the volume in the graduated cylinder? Always estimate and measure at the bottom of the meniscus between lines!

Accurate measurements So the volume is 52.8 mL.

Let’s try again… What is the reading on the triple beam balance shown below?

Let’s try again… What is the reading on the triple beam balance shown below? Remember to estimate between the lines!

Let’s try again… Remember to estimate between the lines!

Let’s try again… So the reading is 373.34 g

Let’s try again…

Let’s try again… The reading is 6.75 mL

And again…

And again… The reading is 2.34 cm

So…. For any measurement (except for electronic measurements), be sure that you estimate one extra digit when you record your measurement by estimated between the lines of the smallest increment on your measuring device.