# Drill accuracy grade by sanmelody

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```									                     Drill
Part 1- A single single unit conversion
Convert 0.1 (or 10-1) m to ___ cm. Give answer in
scientific notation.

Part 2 - Draw 3 dart boards
• On one, show 6+ darts that have accuracy (on
average), but no precision
• On another, show 6+ darts that have precision
but no accuracy
• On the last, show 6+ darts that have accuracy
and precision.
Target analogy

Accuracy
(on
average)
but no
precision
Target analogy

Precision,
but no accuracy
Target analogy

Accuracy
& Precision!
Extra credit assignment
due Wednesday 9/27
• Make a cartoon poster for one safety rule.
• If it looks good enough to me, I will
laminate it & put it up in the classroom.
• It should be:
– No dialogue, just pictures with the safety rule
as a caption underneath
– Big enough to see from across the room
– Funny is good, but it needs to be clearly
related to the safety rule.
Accuracy ≠ Precision!!!
• If there is accuracy  does not
necessarily mean there is precision.

• If there is precision  does not
necessarily mean there is accuracy.
Making precision quantitative
• Scientists speak in numbers a lot.
•          1 = 1.000 000 000?
– Not for scientists!
• Which number is more precise?
• So what?
Which would you prefer?
Copy & circle column A or B.
A                       B

Salary = \$1,000/wk    Salary = \$1000.00/wk

A few grams of        3.000 grams
chemotherapy drug     chemotherapy drug

\$2 Bag of chips       \$2.50 Bag of chips
mass = 500 g
mass = 500.1 g
Making precision quantitative
• When making a measurement, the data
should only include meaningful numbers,
based on how precise the machine is.
• Pour exactly 101 L several times into a
– 100.1L, 101.2 L, 103.9 L,102.0 L
• Which numbers change? Which stay the
same?
• Machine is precise only to tens place.
Significant Digits (Sig. Dig.)
• AKA Significant Figures (Sig. Fig.)
• Sig Fig = # of meaningful numbers plus 1st
number that has uncertainty:
• GC from last slide:
– 100.1L, 101.2 L, 103.9 L,102.0 L
• 1st number of uncertainty is in singles’ place.
• So, when measuring a volume around 100 L in
this GC, write down 3 # or 3 Sig. Fig.
– 100 L, 101 L, 104 L,102 L
Class examples
• 4 meausurements: