1. “How do you evaluate data and conclusions to determine the validity of
Essential Question
“How do you evaluate data
and conclusions to
determine the validity of
research?”

2. Objectives
1. Define SI base units for time, length, mass and temperature.
2. Explain how adding a prefix changes a unit.
3. Compare the derived units for volume and density.
4. Express numbers in scientific notation.

3. Objectives 5. Define and compare accuracy and precision;
6. Use significant figures and rounding to reflect the certainty of data;
7. Use percent error to describe the accuracy of experimental data;
8. Interpret graphs.

4. Significant Figures 1. All digits that are not zero, are significant.
45678  5sf
2. Zero’s between non – zero digits and significant numbers.
7804  4sf
 7 sf

5. Significant Figures
3. Zeros to the left of the 1st non – zero digit are not significant.
 2 sf
4. Zeros to the right of a decimal point are significant if the right of a decimal point are
significant if they are at the end of the number.
 4 sf
777.0  4 sf

6. Significant Figures 5. Always assume zeros at the end of a
number to be non-significant
Compare 3400 and
3400 has 2 sig fig
has 5

7. Addition and Subtraction
When adding or subtracting numbers, the answer should have as many places of decimal as the smaller or smallest place of decimal in the numbers being added or subtracted.
Example:
= 60.4 NOT
should only have 1 place of decimal.

8. Multiplication and Division
When multiplying or dividing numbers, the answer should have significant figures as many as the least number of significant figures in the numbers being multiplied or divided.
For example: x 1.2 x 2.23 = 65 NOT

9. Division Example 465.75/45.6 must have 3 significant figures.
Therefore, /45.6 = 10.2
NOT ….

10. Combined Multiple Operations
If a problem combines addition or subtraction and multiplication or division, apply rules separately.
That is, use places of decimal for addition and subtraction and significant figures to multiplication and division portion of the problem.

11. Combined Multiple Operations
Example
(9.12 – 8.9)/8.9 = 0.2/8.9 = 0.02
Note: (9.12 – 8.9) = 0.2 based on 1 pld
0.2/8.9 = 0.02 based on 1 sf in 0.2