GRAPHING organize present What is a graph? A visual way to _______________ and _______________data organize present

Advantages of Graphs Helps visualize data patterns relationships ____________________ Faster than reading information Can see ___________ quickly Understand ______________ between variables patterns relationships

The three types of graphs are:

What does a line graph show? A measured quantity of change with ___________ or __________ Example: Hourly temperature changes in a day time distance

When is a bar graph useful? When combining data from one thing at __________________ Example: monthly rainfall different times

What two things does a pie graph show? How a quantity can be subdivided A ____________ between quantities Examples: Population of a state in the US Percent of minerals in the crust comparison

X and Y axis

Dependent/Independent Variables Independent Variable – a fixed variable, it is __________________ by the other variables you are trying to measure Examples – time, age, altitude, distance, etc. Dependent Variable – is __________ by the independent variable (it DEPENDS on it!) Examples – temperature, test scores, etc. NOT changed What is a variable? It’s the category you are trying to measure Ind = variable that is manipulated/changed to affect the other variable dep = variable that is changed affected

Time spent studying vs. test score Could your test score have affected/changed the amount you studied the night before? NO Could how much you studied the night before affect/change your test score? YES Independent variable = time spent studying Dependent variable = test score

Examples: A student is curious to find out if how old you are affects how many hours of t.v. you watch daily A scientist conducts an experiment to test the theory that a vitamin could extend a person’s life-expectancy For last two examples talk about where each one would go on graph (x/y axis) A science class is testing whether the amount of sunlight a plant is exposed to affects how tall it gets after one week

What is ALWAYS required on a graph? TITLE! Labeled x and y axis (with units!) Proper scale Key (if using two different sets of data)

How to determine a title Should clearly tell what the graph is about Galena Samples Mass (g) Volume (mL) 5.0 25 9.2 46 14.8 74 18.3 91.5 23.0 118

Determining scale Step 1: find the range in values Greatest value – smallest value = range in values Step 2: count number of units (squares/boxes) on graph Each box equals 1 unit Step 3: divide number of units by the range in values

Galena Samples Mass (g) Volume (mL) 5.0 25 9.2 46 14.8 74 18.3 91.5 Step 1: find the range in values Greatest value – smallest value = range in values 23.0 – 5.0 = 18 Step 2: count number of units on graph Each box equals 1 unit There are 36 units Step 3: divide the number of units by the range in values 36/18 = 2 Every 2 units is 1 gram on graph Galena Samples Mass (g) Volume (mL) 5.0 25 9.2 46 14.8 74 18.3 91.5 23.0 118 Both scales do NOT need to be the same scale on both axes!

Determining scale DO NOT The x and y axis ____________ need to have the same scale Try to use up as much of the allotted graph space DO NOT

What are some types of change that we could see on graphs? Increase Decrease Increase  decrease  increase Cycles No change over time

Positive Relationship As the independent variable increases, the dependent variable ___________ The two variables are directly related – ______ RELATIONSHIP Examples: age vs. height, mass vs. volume increases Direct relationship – an increase in one variable, increases the other variable DIRECT

Negative Relationship As the independent variable increases, the dependent variable __________ The two variables are indirectly related- ___________ RELATIONSHIP Example: elevation vs. average temperature decreases Variables move in opposite directions! INDIRECT

Constant Relationship As the independent variable increases, the dependent variable ______________ One variable remains constant – ____________ RELATIONSHIP Example: time of year vs. rotation speed of Earth stays the same STATIC How tall you are/ how much you grow and whether or not you have a nose

Cyclic Relationship pattern CYCLIC As the independent variable increases, the dependent variables increases and decreases in a __________ Dependent variable goes through cycles – ____________ RELATIONSHIP Repeatable and predictable Examples: tides on a beach, phases of the moon pattern CYCLIC Repeatable and predictable

What type of relationship does this data represent? Altitude (ft) Pressure 1000 650 925 1200 800 1900 698 2500 535 3100 375 3800 200

What type of relationship is this? A scientist wanted to study whether the population of a given area affects the amount of pollution in the air there. She found that the denser a town is, the more polluted it will be. This is an example of what type of relationship? DIRECT! We will extrapolate from this data

What type of relationship is this? A student plotted the average monthly temperature for 36 months (3 years) straight. He noticed that during the summer months, the temperature was always hotter than during the winter months. This is an example of what type of relationship? CYCLIC!

What type of relationship is this? A student wanted to see if a sample of marble would change mass over time. He weighed the sample once every week for 3 months. He discovered that the mass of the rock did not change over his period of study. This is an example of what type of relationship? STATIC!

Its safe to assume that whatever relationship we see on a graph will continue for the data points that are not on there – how you extrapolate What is the relationship between relief (or slope) and the average rate of erosion? As relief increases, the average rate of erosion increases --- DIRECT RELATIONSHIP