“Drawing Results from Observations by Graphing Data”

Ø If you are going to make a scientific graph using Microsoft Excel get the Excel handout

Ø If you are going to make a scientific graph manually using graph paper get "manual graphing with graph paper " handout.

Graphs are a useful tool in science. The visual characteristics of a graph make trends in data easy to see. One of the most valuable uses for graphs is to "predict" data that is not measured on the graph.

Extrapolate: extending the graph,

along the same slope, above or below measured data.

Interpolate: predicting data between two measured

points on the graph.

Constructing a Graph Manually with Graph Paper

How To Construct a Line Graph On Paper

Step	What To Do	How To Do It
1	Identify the variables	a. Independent Variable - (controlled by the experimenter) · Goes on the X axis (horizontal) · Should be on the left side of a data table. b. Dependent Variable - (changes with the Independent variable) · Goes on the Y axis (vertical) · Should be on the right side of a data table.
2	Determine the variable range.	a. Subtract the lowest data value from the highest data value. b. Do each variable separately.
3	Determine the scale of the graph.	a. Determine a scale, (the numerical value for each square), that best fits the range of each variable. c. Spread the graph to use MOST of the available space.
4	Number and label each axis.	This tells what data the lines on your graph represent.
5	Plot the data points	a. Plot each data value on the graph with a dot. b. You can put the data number by the dot, if it does not clutter your graph.
6	Draw the graph.	a. Draw a curve or a line that best fits the data points. d. Most graphs of experimental data are not drawn as "connect-the-dots".
7	Title the graph	a. Your title should clearly tell what the graph is about. b. If your graph has more than one set of data, provide a "key" to identify the different lines.

Graphing resources:

· Graph Paper*

Ø For log graph paper go to http://www.engj.ulst.ac.uk/sidk/graph/graph.htm

Ø Basic arithmetic graph paper go to http://faculty.plattsburgh.edu/edwin.romanowicz/images/arithmetic.pdf

Ø For coordinate plane graph paper go to http://seawolf.uofs.edu/~monks/courses/GraphPaper.html

Ø If you need some other form of graph paper just search the net using the following phrase, “graph paper” pdf , and include the quotation marks.

* (you will need Adobe Acrobat Reader installed on your computer for most of these files. It can be found on the web for free @ http://www.adobe.com/products/acrobat/readstep.html )