Objectives The student will be able to: ● Distinguish between accuracy and precision ● Use significant figures in measurements and calculations

Accuracy and Precision ● Careful measurements are _________ in science ● No measurement is perfect ● Two terms that describe this imperfection: o Accuracy: the extent to which a reported measurement approaches the ___________of the quantity measured o Precision: the degree of ___________ or refinement of a measurement

Accuracy vs Precision

Sources of Error Problems with accuracy are due to error ● Human Error: Mistakes made in _________ an instrument or recording the results ● Method Error: When measurements are taken using different methods o Parallax: An overestimate or underestimate due to the improper viewing of a measuring device ● ________ Error: Improperly displayed measurements due to poorly calibrated devices

Precision and Significant Figures ● Significant figures (Sig Figs) describe the ____________ of a measuring device ● Significant Figures: those digits in a measurement that are known with certainty ______ the first digit that is _________

Review of Sig Fig Rules Nonzero Digits are __________ significant! 46.3 has 3 sig figs. Zero Rules: ● Zeros between other ___________ digits are ___________ m has three sig figs ● Zeros _____________of nonzero digits are ____ significant m has three sig figs ● Zeros that are _______ at the end of the number and to the ________ of the decimal point are significant has four sig figs ● Zeros at the end of a number, but to the left of the decimal point may not be significant. If the place wasn’t estimated, it’s not significant. *Example: 100 has 1 significant figure*

LETS PLAY: THE SIG FIG IS RIGHT Determine how many sig figs are in the following quantities: SIG FIG

Rules For Calculating Sig Figs ● Addition and Subtraction: o Final answer should have the ________ number of sig figs to the right of the decimal place as the number with the _________ number of digits to the right of the decimal ● Multiplication and Division: o The final answer should have the ________ number of sig figs as the measurement having the __________number of sig figs

Rounding Rule ● If the digit being rounded is less than five, round down ● If the digit being rounded is five or greater, round up

LETS PLAY: THE SIG FIG IS RIGHT... AGAIN! Determine what the final answer would look like after performing the indicated operation for the following questions: x x 74.3 SIG FIG AGAIN

Wrap Up Answer the following questions: ● Why are significant figures important? ● What steps could an experimenter take to ensure that their experiment is as accurate as possible?