How do people gather scientific information?

Scientific Method I’M TAD Identify a Problem Make a Hypothesis Test the Hypothesis (Perform an Experiment) Analyze the Data Draw Conclusions Sometimes a 6 th step is included in which you share your conclusions with others

Hypothesis vs. Theory vs. Law Hypothesis – An educated guess Scientific Theory – A hypothesis supported by many experiments Scientific Law - facts of nature accepted as truth

Controlled Experiments A Controlled Experment is one where only one variable is tested at a time Why is it important to use controlled experiments?

Controlled Experiments Control Group – the group that doesn’t receive the experimental treatment, a standard for comparison Independent Variable – the variable in the experiment you change Dependent Variable – the variable in the experiment that only changes because you changed the independent variable

Controlled Experiments Example: Merck decides to test a new antibiotic to see if it will cure patients’ sinus infections. Some testers are given pills containing the new antibiotic and others are given a placebo, or sugar pill. Identify: Control Independent Variable Dependent Variable

The Metric System In the US, we use the English system of units (lbs, in., oz., etc.) The rest of the world, including the scientific world, uses the SI (Systeme Internationale) or Metric System Why? It’s universal (used everywhere but US) Units are converted based on factors of 10

SI Units What are the SI base units for these measurements? Length/distance? Meter (m) Volume? Liter (L) Time? Seconds (s)

SI Units What are the SI base units for these measurements? Temperature? Kelvin (K), the absolute scale for Celsius (°C) Mass? Grams (g)? We use grams for the base unit, but kilograms (kg) are considered the SI unit for mass

Metric Conversions We use SI units because it’s easy to convert between magnitudes We use a prefix to identify the magnitude of the measurement Examples: kg, cm, mL To remember the prefixes, use the mnemonic: King Henry Died by Drinking Chocolate Milk

Metric Prefixes PrefixSymbolMagnitude Kilok1,000(10 3 ) Hectoh100 (10 2 ) Decada10 (10 1 ) base unitg, L, m1 (10 0 ) Decid0.1 (10 -1 ) Centic0.01 (10 -2 ) Millim0.001 (10 -3 )

Converting between Metric Units To convert between metric units, count how many spaces are between the units Move the decimal point that many spaces in the direction you counted towards Example 1: 10m = ? cm Answer: 1,000cm Example 2: 10mL = ? hL Answer: hL kilohectodecabasedecicentimilli

Density The amount of matter in a given amount of space is known as Density(D) D = m/V Common units: g/mL, g/cm 3 Note: 1mL = 1cm 3 Example: If a 45.2g block has a volume of 11.6mL, what is it’s density? D = 45.2g/11.6mL D = 3.90g/mL

Area A = l x w For a square: A = side 2 For a triangle: A= ½ bh Common units: cm 2, m 2 Example: If a square has a length of 5cm and a width of 3cm, what is its area? A = 5cm x 3cm A = 15cm 2

Matter, Mass and Weight Matter – anything with mass and volume Mass – the amount of matter in an object Weight – the effect of gravity on an object What is the difference between mass and weight? Gravity