GRAPHING

Reading, Constructing, and Analyzing Graphs

Make sure your graph “TALKS” to me!!

T-TitleA-Axis (x axis=independent variable y axis=dependent variable)L-Label (everything should be labeled)K-Key (if appropriate)S-scale (make sure scale of numbers is appropriate-don’t always have to use increments of 1)

Bar Graphs

*easily read, used to graph categories of things, usually have spaces between the bars

**What is this bar graph missing?

Histograms

*similar to bar graphs except the bars represent a range of values rather than one single value and the bars touch each other

*intervals should be equal (1-10, 10-20, etc.)*width of bars should all be the same

Line Graphs*shows change over time or relationship

between 2 quantities*do NOT connect dots after plotting points Draw a “Line of Best Fit” or a “Curve of Best

Fit” -Use the points to draw the best straight line

you can; have the line pass through as many points as possible, with approximately the same number of points on one side of the line as the other

Analyzing Graphs

Interpolation—finding a value that is actually on the graph

Extrapolation-finding a value that lies BEYOND the actual data on the graph

BAR GRAPH PRACTICEUse the following data to create a bar graph.REMEMBER: Make sure your graph “TALKS” to me!!

“Plant Growth: Height Vs Time” Time (days) Height (cm)

5 3 10 8 15 11 20 13

25 19 30 25

Bar Graph Questions

Interpolation: What is the independent variable for this

graph? How tall was the plant after 10 days?Extrapolation: How tall do you think the plant will be after

day 40? Explain.

Histogram Practice

Use the data to create a histogram.REMEMBER: Make sure your graph “TALKS” to me!

DATA ON THE NEXT SLIDE!

Life Expectancies in the US

Current Age Remaining Years Expected0-10 72.611-20 59.521-30 50.131-40 40.741-50 31.751-60 23.261-70 15.871-80 9.781-90 4.5

Histogram Questions

Interpolation: Mrs. Parker is 38 years old. About how many more years can she expect to live according to the graph?

Extrapolation: Make a prediction about the remaining years of life that would be expected for someone in the current age category of 91-100. Justify your answer. (Give specific information!)

Line Graph Practice

Use the data on the next slide to create a line graph.

Remember: Make sure your graph “TALKS” to me!

Do NOT connect the points after plotting them; Draw a “Line of Best Fit” or a “Curve of Best Fit”

Time Vs Position of a Miniature Motorized Car on a Straight Track

Time (minutes) Position (meters)

0 0 5 15 10 30 15 45 20 60 25 75

Line Graph Questions

Interpolation: What is the independent variable for this graph?What is the dependent variable for this graph?Determine the position of the car after 2.5 minutes.Extrapolation:If the experiment was conducted for 35 minutes, what

would be the position of the car?How many minutes will it take the car to reach the

position of 180 meters?

Scientific Graphs

Most of the time, scientists use line graphs instead of the bar graphs; therefore, we will be using line graphs in science.

You are too young for bars, anyway!!!

FIST OR FIVE??

Show me a fist if there is something we have covered about graphs that you still don’t understand.

Give me a five if you are comfortable with bar graphs, histograms, and line graphs.