Graphs in Science p. 34

Objectives Explain what type of data line graphs can display Describe how you determine a line of best fit or slope o a graph Explain why line graphs are powerful tools in science

Importance of Graphs Graphs are a way to show data A GRAPH is a picture of your data Graphs can reveal patterns or trends that words and data tables cannot

Why are line graphs useful? Line graphs can reveal more data more clearly Line graphs are used to display data to show how one variable ( the responding variable) changes in response to another variable (the manipulated variable). **Draw data table on p. 35. Explain what is occuring

Plotting a line You should use a line graph when your manipulated variable is continuous. (When there are points between the ones tha tyou tested) To plot a line graph of your data do the following Draw the axes: horizontal axis and vertical axis Label the axes Create a scale: make sure to include the origin and coordinates Plot the data: make sure to use the data point showing the locations of intersections Draw a “line of best fit” Add a title Copy examples on p. 37

Why draw a line of best fit? A line that best fit emphasizes the overall trend shown by all the data taken as a whole

Slope Slope is the steepness of the graph line The slope of a graph line tells you how much y changes for every change in x Slope= rise/run=y₂-y₁/x₂-x₁

Using Graphs to Identify Trends A line graph in which the data points do not fall along a straight line is call a nonlinear graph Line graphs are powerful tools in science because they allow you to identify trends and make predictions Linear trends are when you can easily see how two variables are related Nonlinear trends are when you have points that may fall on the graph showing a curve No trend is when the points are scattered and there are no recognizable patterns Copy graphs p. 40-41