Measurement

Part 1: Interpreting Measurements

Types of Data Science relies on collecting and analyzing data. Two main types of data: Qualitative data – can be observed but not measured Examples: colors, textures, smells Called qualitative because it describes the quality of something

Types of Data Quantitative data – can be measured and expressed in numbers. Examples: length, speed, time, temperature Called quantitative data because it measures the quantity of something

The SI system Quantitative data is measured using the International System of Measurement (SI) Also known as the metric system Benefits: Based on units of 10 (makes multiplying and dividing easier) Universal (used internationally by scientists)

SI Prefixes Base Unit Symbol Measures Meter length m mass Gram g Base units: fundamental units of measurement Base Unit Symbol Measures Meter length m mass Gram g volume Liter L Second s time

SI Prefixes SI prefix –a word that precedes a base unit and indicate multiples Prefix Symbol Meaning Multiplication Scientific Notation Thousand 1 x 10 x 10 x 10 1 x 103 Hundred 1 x 10 x 10 1 x 102 Ten 1 x 10 1 x 101 BASE UNIT Tenth 1/10 1 x 10-1 Hundredth 1/(10 x 10) 1 x 10-2 Thousandth 1/(10 x 10 x 10) 1 x 10-3 Kilo- k h Hecto- Deca- da Deci- d Centi- c Milli- m *NOTE: k, c, and m are the prefixes used most often in science.

Metric Conversions Example: Convert 25 cm to m. Mnemonic: King Henry Died By Drinking Chocolate Milk

Practice

Scientific Notation Used to represent very large or very small numbers Expressed as a number 1-10 multiplied by a power of 10 Example: 2.4 x 103, 7.8 x 10-5, etc. Exponent shows the number of places to move the decimal Positive exponent – the original number was greater than zero; decimal moves to the right 1.25 x 104 = 12500 Negative exponent – the original number was less than zero; decimal moves to the left 1.25 x 10-4 = 0.000125

Practice 4.7 x 104 = __________ 6.2 x 10-3 = ___________ 47000 .0062

Part 2: making Measurements

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Length Distance between 2 points -- Meter (m) ruler, meter stick

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Area Amount of surface A = length x width m x m = m2 “ “

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Volume of solids Amount of space an object occupies V = length x width x height m x m x m = m3 “ “

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Volume of liquids Amount of space a liquid occupies 1 mL = 1 cm3 Liters (L) beaker, graduated cylinder

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Mass* Amount of matter in an object -- grams (g) triple beam balance

Mass versus weight: Weight is how hard gravity pulls on an object * Mass versus weight: Weight is how hard gravity pulls on an object. Things weigh less on the moon because gravity is weaker there (only 0.165 times that of Earth). Mass is the amount of matter in an object—which doesn’t change based on location. https://www.youtube.com/watch?v=-F5nmIJOF4U

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Density amount of matter that occupies a given space D = mass/volume Solids: g/m3 Liquids: g/L triple beam balance + ruler/meter stick OR beaker/grad. cylinder

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Time interval between 2 events -- Seconds (s) stopwatch, clock

Equation (if applicable) Parameter Definition Equation (if applicable) SI base unit Measuring Tools Temperature amount of heat in an object K = °C + 273 Kelvin (K) or degrees Celsius (°C) thermometer

Graphing

Graphs: Essentials Each graph must have: Tip: do your graphs in pencil title labeled axes appropriate scale (spacing between numbers) legend (AKA, key) if more than two data sets appear on graph Tip: do your graphs in pencil

Three types of graphs Line graphs – show how two variables are related; is the most common graph we’ll use in class Used to answer questions like How does x affect y? How does something change over time?

Three types of graphs Bar graphs – compares groups or categories of data Used to answer questions like: How does this group compare to another group(s)?

Line, Bar, or Pie? Line graph! Value of Sarah's Car Age (years) Value 1 $24,000 2 $22,500 3 $19,700 4 $17,500 5 $14,500 6 $10,000 7 $ 5,800 Line graph!

Line, Bar, or Pie? Line graph!

Students' Favorite After-School Activities Line, Bar, or Pie? Students' Favorite After-School Activities Activity Number of Students Play Sports 45 Talk on Phone 53 Visit With Friends 99 Earn Money 44 Chat Online 66 School Clubs 22 Watch TV 37 Bar graph!

Types of Vascular Plants in NC Line, Bar, or Pie? Types of Vascular Plants in NC Taxonomic group Percentage Ferns 4% Gymnosperms 1% Monocots 35% Dicots 60% Pie chart!

Graphing Step 1 – Determine the variables and label each axis Dependent variable goes on the y-axis (vertical) Independent variable goes on the horizontal x-axis (horizontal) “Why (Y) be dependent when your Ex (X) is independent?” Y-Axis Dependent Variable X-Axis , Independent Variable

Graphing Step 2 -- Determine the scale of the graph Scale = the number value for each square on the graph Spread the graph out to take up the most maximum amount of space

Graphing Step 3 -- Plot the data points, marking each data value with a dot Step 4 -- Draw the graph If there is more than one line on the graph, you must include a key identifying each line

Graphing Step 5 -- Give the graph a descriptive title Acceptable title: The Effect of Sleep on Test Grades Unacceptable titles: “Sleep and Grades,” “Test Scores and Sleep”