The document discusses key concepts related to graphing data, including the purpose of graphing, dependent and independent variables, and interpolating and extrapolating. It defines dependent and independent variables and provides examples of graphing height against number of boxes and lamps. It also explains that a straight line graph indicates a constant relationship between variables, while a non-straight line shows a changing relationship, and interpolated/extrapolated data is more reliable for a straight line graph.

1. While reviewing this presentation answer the following questions. Explain to me what the purpose is behind graphing. What are Dependent and Independent Variables ? What does it mean to interpolate and extrapolate? What does a straight line in a line graph mean?

2. Why do we graph data? To show the relationship between the graphed variables. (Without calculations) To gain interpolated and extrapolated data. “ inter” – in between data points. “ extra” – outside of data points.

3. Graphing is NOT: Easier – Quitting after data collection is easier than graphing the data! More visual – A data table is also a visual! More organized – A data table is organized, by its very design!

4. Rules for Graphing Label x and y axes. Include units. Title your graph. (y vs. x will always work if you can’t be more descriptive!) Number axes consistently and consecutively. Use > 75% of each axis. Plot data with a fine, accurate point. Circle data points so they are easily located. Connect data points with a smooth curve or with a line of best fit.

5. Dependent and Independent Variables The Dependent variable is always assigned to the y-axis . relies on the changes in the independent variable. The dependent variable is what we measure . The Independent variable is always assigned to the x-axis does not relying on an other variable. The values of the independent variable can be chosen freely.

7. Sample data for graphing Height vs. # of boxes # of boxes height (m) 1 0.5 2 1.0 3 1.5 4 2.0 5 2.5 6 3.0 Height vs. # of lamps # of lamps height (m) 1 0.4 2 1.0 3 1.3 4 2.1 5 4.1 6 4.5

8. If graphed data forms a straight line… Shows a constant relationship between the variables. Interpolated and extrapolated data is reliable. What was graphed was consistent or uniform.

9. If graphed data does not form a straight line… Shows a non-constant (changing) relationship between the variables. Interpolated and extrapolated data is unreliable. What was graphed was not uniform.

10. Interpreting the Graphs Which graph would give more reliable interpolated and extrapolated data? If I had 7.5 m of stacked boxes, how many boxes would I have? Approximately how tall would a stack of 7 lamps be? How many boxes could I stack in a room with a 4 m ceiling?