1. Measure a paperclip using each “ruler”.

2. Discuss with group members:A)
Which ruler allowed you to make the most precise measurement?
How does the measurement (numbers only) itself reflect precision of measurement tool?
In your own words, define the following:
Precision
Accuracy
significant digits
uncertainty
Is there such thing as a “perfect measurement”? Why or why not?
How is measurement uncertainty determined? B) C)

3. Question #1: Which ruler allowed you to make the most precise measurement?

4. Question #1: Which ruler allowed you to make the most precise measurement?
The third ruler (with most markings) allowed for the most precise measurement.
Precision= consistency.
More markings means more “consistency” with multiple trials

5. Question #2: How does the measurement reflect precision of measurement tool?

6. Question #2: How does the measurement reflect precision of measurement tool?
The more non-zero digits, or zeroes after a decimal point, a measurement has, the more precise it is.
It shows that you were able to measure to a more precise number

7. A proper measurement has all certain digits (using markings) plus one estimated digit (beyond smallest marking)
All numbers in a measurement are “significant digits” if they constitute as either of the above.

8. Question #3: Define the following:

9. Question #3: Define the following:
Precision: how close two or more measurements are to each other; consistency in measurements
Accuracy: how close to a standard or known value a measurement is
Significant Digits: All certain digits plus one estimated digit
Uncertainty: range that reflects where the true value of a measurement is most likely to fall

10. Question #4: Is there such thing as a “perfect measurement”
Question #4: Is there such thing as a “perfect measurement”? Why or why not?

11. There is no such thing as a perfect measurement.
Question #4: Is there such thing as a “perfect measurement”? Why or why not?
There is no such thing as a perfect measurement.
There are inherent errors in the tool (systematic error) and person making the measurement (random error)

12. Question #5: How is measurement uncertainty determined?

13. Question #5: How is measurement uncertainty determined?
Determine the increment between measurement intervals on the measurement tool.
Divide the increment by two
Round up
Have only one non-zero digit

14. What’s the precision and uncertainty?
Meaning, to how many digits should the measurement read?
What’s the precision and uncertainty?
For each of the following images, determine the precision and uncertainty of the tool.
TOOL
PRECISION
UNCERTAINTY
1. Pipette
2. Beaker
3. Grad. cylinder
4. Flask
5. Thermometer
TOOL
PRECISION
UNCERTAINTY
6. Stop watch
Ruler
8. Beaker
9. Grad. cylinder
10. Thermometer

19. (use Celsius)

21. How many digits in cm? Uncertainty in cm?

22. How many digits? Uncertainty?

23. How many digits? Uncertainty?

24. How many digits? Uncertainty?
Reads 20 and 30

25. But… 1. Glass cylinder Hundredths +/- 0.05 mL Beaker Tens +/- 20 mL
TOOL
PRECISION
UNCERTAINTY
1. Glass cylinder
Hundredths
+/ mL
Beaker
Tens
+/- 20 mL
3. Graduated cylinder
Tenths
+/- 0.5 mL
Flask
Ones
+/- 5 mL
Thermometer
+/- 3°C
6. Stop watch
+/ s
But…
7. Ruler
Hundredths
+/ cm
8. Beaker
Tens
+/- 50 mL
9. Graduated cylinder
Tenths
+/- 0.5 mL
10. Thermometer
+/- 0.5°C

26. Mini-Lab: Precision Practice
Put this mini-lab into your table of contents.

27. Precision Practice Visit lab stations. Observe 30 measuring devices.
Determine precision and uncertainty.
Create in a table to record tool name, uncertainty and precision in your lab book.
It’s ok if you don’t finish as long as you work productively.