Warm Up Hw on desk. Work silently. 1.If I measure volume as 3 mL and the true volume is 4 mL, what is the percent error? 2.A student measures density 3 times and gets 4.50, 4.40, and If the literature value of the density is 6.0, then evaluate the data.

Accuracy = getting the right answer ON AVERAGE Other words for “right answer” True value Accepted value Actual value Textbook value Literature value

Accurate or not? TrialMeasurement Average = 6.0 Literature Value= 6.03

Precision = getting the SAME answer again and again

Precise or not? TrialMeasurement Average = 5.53 Textbook Value= 7.10

Percent error Percent error= Tells you how far off your measurement is.

Accuracy, Precision and % Error Percent Error %E = V actual – V measured X 100 V actual | |

Accuracy, Precision and % Error % error: Measuring a string you get 18 cm, but Mr. McKnight tells you the string is actually 20 cm long.

Criteria To be MATTER it… 1.Must be made of stuff 2.Must take up space

Jigsaw Each # take notes in your corner then return to your group and teach what you’ve learned. Then take notes on what your group members teach you. #1 front left #2 front right #3 back left #4back right When finished, all raise hands to check with me

Practice Scavenger hunt to find the definitions of 10 of your group’s unknown words from the jigsaw Process your words by drawing a picture, using it in a sentence, or rephrasing the definition in your own words Using the definitions, classify the changes and properties on papers around the room as physical or chemical

Jigsaw Each # take notes in your corner then return to your group and teach what you’ve learned. Then take notes on what your group members teach you. #1 front left #2 front right #3 back left #4back right When finished, all raise hands to check with me

Stations Classify the items or examples at each station as: –An element –A compound –A homogeneous mixture –A heterogeneous mixture Write a brief reason If there isn’t enough info to tell, write what you need to know to be able to classify that example

Synergy Exercise Work in your group to rank items based on survival usefulness Must come up with one ranking How’d your group do? Reflection

HW Half sheet- ID elements, compounds, mixtures Top Ten: how’d we do?

Exit slip Define compound. Give example Define mixture. Give example Define element. Give example