Warm Up September 12, 2013 This is…well…not the greatest graph ever (to put it nicely). How could you improve this graph?

Warm Up September 12, 2013This is…well…not the greatest graph ever (to put it

nicely). How could you improve this graph?

Correct HW

Quiz #3

1.5 Graphs in Science

• There are many types of graphs. In Life Science last year, you may have used bar graphs or pie charts often.

• In chemistry and physics, the type of graph that is used most often is the line graph.

Charles Law of Gas Behavior in chemistry

Distance vs time graph in physics

• A line graph shows how one variable changes in response to another.

Line graphs are used when the manipulated or independent variable is continuous.

Continuous Independent Variable

• A bar graph is used when the manipulated or independent variable is not continuous but has multiple, distinct forms.

Parts of a Line Graph

• X axis• Y axis• Scale• Title• X axis label• Y axis label• Data points• Line of best fit• Key (if multiple sets of data points are on the same

graph)

The Effect of Time on Ice Sheet Area

Steps in Creating a Line Graph

• 1. Draw the axes. ;)

2.

3. Create a Scale

• Choose a scale that fits your data points.• Have consistent intervals. • Your data points should fill most of the graph.

(if the points are too close together, it is hard to see a trend. Everything looks like a line from far enough out – even the Milky Way Galaxy!)

• The scale does not have to start at zero.

4. Plot the Data

5. Add a Title

• Your title should follow the format:

“The Effect of (independent variable) on (dependent variable).”

Capitalize all major words in the title. You do not need to capitalize words like “the”

and “of”.

6. Draw a Line of Best Fit

• The line of best fit is a line that most closely fits a set of data points.

Why draw lines of best fit?

• A line of best fit can:– Help you see the overall

trend– Help you to recognize

outliers, or points that may not be accurate

– Allow you predict results for data you have not yet collected

How to draw a line of best fit:

1. Plot all measured data points on a graph.1. Make sure independent variable is on x axis.2. Make sure dependent variable is on y axis.

2. Using a ruler, draw the line that deviates the least from the set of points.

3. Choose two points on the line (they do not have to be data points you measured – just any two points on the line) and use them to calculate the slope.

Calculating Slope

Example

Trends in Graphs

• Linear Trend: Data points are in a straight line and a line of best fit can be applied.

• Say or Write: “As (independent variable) increases/decreases, (dependent variable) increases/decreases.”

Example

“As temperature increases, volume increases.”

Nonlinear Trends: Curves

• For some sets of data, drawing a curve is the best way to represent the data points.

• Say or Write: “As (independent variable) increases/decreases, (dependent variable) increases/decreases SHARPLY ”

Example

As pressure increases, volume decreases sharply.

“These Old Bones” Graphing Investigation

Homework

• p. 41 #1a-c, #2a-c, & #3a-b• Finish “These Old Bones” Lab