1. Measurements in Science Chapter 1

2. Accuracy and Precision Accuracy: A description of how close a measurement is to the rue value of the quantity measured. Precision: The exactness of a measurement.

3. Qualitative vs. Quantitative Data Qualitative Data: data that is descriptive but cannot be measured on a numerical scale Quantitative Data: data measured or identified on a numerical scale. Some data are both quantitative and qualitative Examples (qualitative or quantitative?): “The temperature in this room is 23 degrees Celsius." “The temperature in this room is 23 degrees Celsius." “This room is warmer than it is outside". “This room is warmer than it is outside". “The tree is taller than the building." “The tree is taller than the building." "The tree is 30 feet tall." "The tree is 30 feet tall."

4. A Common Measurement System Because scientists communicate with other scientists all over the world, they must use standard units. This system of standard units is the International System of Units (SI). It is commonly called the metric system.

5. A Common Measurement System The SI base units are: Temperature is the degree Celsius ( o C) Length is the meter (m) Mass is the kilogram (kg) Time is the second (s) Volume is the liter (L)

6. KILO 1000 Units HECTO 100 Units DEKA 10 Units DECI 0.1 Unit CENTI 0.01 Unit MILLI 0.001 Unit Meters Liters Grams Ladder Method How do you use the “ladder” method? 1 st – Determine your starting point. 2 nd – Count the “jumps” to your ending point. 3 rd – Move the decimal the same number of jumps in the same direction. 4 km = _________ m 1 2 3 How many jumps does it take? Starting Point Ending Point 4. 1 __. 2 3 = 4000 m

7. Try these conversions using the ladder method. 1000 mg = _______ g 1 L = _______ mL160 cm = _______ mm 14 km = _______ m109 g = _______ kg 250 m = _______ km Conversion Practice Compare using, or =. 56 cm 6 m 7 g 698 mg

8. A Common Measurement System Other prefixes that are used by scientists: tera (T) = 1 trillion tera (T) = 1 trillion giga (G) = 1 billion giga (G) = 1 billion mega (M) = 1 million mega (M) = 1 million nano (n) = 1 billionth nano (n) = 1 billionth pico (p) = 1 trillionth pico (p) = 1 trillionth

9. Graphing Numerical data collected from an experiment is arranged into a data table so that its information can be read quickly. Example: The following hair colors were found among three classes of students: Example: The following hair colors were found among three classes of students: Class 1: brown = 20 black = 1 blonde = 4 Class 2: brown = 18 black = 0 blonde = 6 Class 3: brown = 15 black = 4 blonde= 15

10. Graphing A line graph is best for displaying that change. A line graph usually consists of two axes upon which the different variables of the experiment are graphed: A line graph usually consists of two axes upon which the different variables of the experiment are graphed: The independent variable is always placed on the X axis. The dependent variable is always placed on the Y axis.

11. Graphing A bar graph is useful when you want to compare data for several individual items or events.

12. Graphing A pie chart or circle graph is ideal for displaying data that are parts of a whole.