Measurement Lab 2 Significant Figures Calculations

Objectives: Informal Assessment: Formal Assessment: Use proper technique to make accurate and precise measurements. Apply the rules for significant figures to calculations. Informal Assessment: Monitoring student interactions and questions as they complete the measurement lab and significant figures practice Formal Assessment: Analyzing student responses to measurement lab and significant figures practice Common Core Connection Use appropriate tools strategically Attend to precision Make sense of problem and persevere in solving them

Lesson Sequence Evaluate: Warm-Up Explain: Measuring to the Correct Sig Figs Elaborate: Measurement Lab Trial 2 Evaluate: Significant Figures Inquiry Elaborate: Significant Figures Practice Explain: Significant Figures Calculations Elaborate: Significant Figures Calculation Practice Evaluate: Exit Ticket

Warm - Up Measure the length of the index card on your desk What unit did you measure the length in? How many decimal places did you measure it to? Why did you measure it to that number of decimal places?

Objectives: Today I will be able to: Use proper technique to make accurate and precise measurements. Apply the rules for significant figures to calculations.

Homework Finish Significant Figures Calculations WS Study for Significant Figures Quiz on Wednesday, September 3

Agenda Warm-Up Measuring to the Correct Sig Figs Measurement Lab Trial 2 Significant Figures Inquiry Wrap-Up Significant Figures Practice Significant Figures Calculations Significant Figures Calculation Practice Exit Ticket

Draw this table on the back of your measurement lab Lab Equipment Unit of Measurement (cm, g, mL, etc.) Number of Decimal Places it Can be Read to Ruler/ Meter Stick Balance Beaker Graduated Cylinder Erlenmeyer Flask Complete the table and if you are having trouble look at your trial 1 measurements from yesterday

Measurement Lab Trial 2 Travel to the stations in the lab and measure the mass, volume or length to the correct number of decimal places. DON’T Record the number of sig figs in your trial 2 measurement. Record 3 of your measurements on the board

Class Discussion How do the trial 2 measurements differ from the trial 1 measurements? Why are significant figures important?

Take out the Sig Fig Inquiry Worksheet Wrap-Up of the Sig Fig Rules

Significant Figure Notes

Atlantic Pacific Rule

Atlantic Pacific Rule If a decimal point is Present as in 52.3 km, count from the “Pacific Side” from the first nonzero digit to the end. Meaning, count from the left side of the number 52.3 has 3 sig figs How many sig figs in .0093077 There are 5 sig figs (start counting at 9)

Atlantic Pacific Rule If the decimal point is Absent, as in 1530 g, count from the Atlantic Side beginning with the first nonzero digit and going to the end, counting any zero as significant. This means start from the right - 1530 g has 3 sig figs How many sig figs in 190,542,100ml - There are 7 sig figs

Examples .0026702 m - 5 19.0750 kg - 6 25,000,000, 000 mm - 2 1,908,150 L - 6 520 ml - 2 .0102 ns - 3

Sig Fig Calculations You cannot be more precise than your least precise measurement In multiplication and division, the measurement with the smallest number of sig digits determines how many digits are allowed in the final answer If you have several steps, carry the extra digits. Only the final answer is rounded

Examples Your answer can only have 3 sig figs 6.15 m x 4.026 m = ? 6.15 m has 3 sig figs 4.026 m has 4 sig figs Your answer can only have 3 sig figs 24.7599 m2  24.8 m2

Examples .03287 g x 45.2 g = ? 45.2 g has 3 sig figs Your answer can only have three sig figs 1.485724 g  1.49 g

Final Note When doing calculations with significant figures, conversion factors do not figure in Counts and defined numbers are EXACT and have no uncertain digits Example: if you say there are 6 people in your family it is a counted number and is considered certain. There are not 6.1 people in your family Example: 12 inches = 1 foot is defined – do not use significant figures. 1 foot will never be 11.99 inches. In both cases, significant figures do not apply

Significant Figures Calculation Practice Complete the practice at your desk. Problems not completed in class will become your homework.

Exit Ticket Complete the calculation to the correct number of sig figs. 4.21 X 5.5270 = 5.126 – 2.2 = Icebreaker: If you could turn yourself into something different (car, animal, plant, etc) for one week, what would it be? Would you rather be 4 inches tall or 100 ft tall?