Accuracy Precision Precision
How close a measurement is to the true value of the quantity being measured Accuracy Example: The experiment calls for 1.5 mL of water. Jackson measure 1.5 mL of water.
Precision Exactness of the measurement Example: Bridget Example: The experiment calls for 5.25 cm of rope. Kristin cuts 5.25 cm of rope.
Accurate and Precise Precise but NOT Accurate Accurate but NOT Precise NOT Accurate and NOT Precise
Practice! • Tom is playing soccer and he always hit the left goal post instead of scoring. • For a science fair project, Amy wants to measure the voltage of different batteries and see how they compare. She starts with a 9 volt battery and gets a reading of 3.4 volts. Thinking her measurements were wrong, she measure it 5 more times, each time getting 3.4 volts. • Melissa and Janie need to make 150 mL of soup for their sick grandmother. The can says it holds 150 mL. However, once the girls opened the can they realized it only had 150 mL of soup.
Do you REALLY get it? • Write a situation that is: • Accurate and precise • Accurate but not precise • Precise but not accurate • Not accurate and not precise Make sure to write in complete sentences and illustrate each situation.
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