Scientific Graphs: Most scientific graphs are made as line graphs. There may be times when other types would be appropriate, but they are rare. The lines on scientific graphs are usually drawn either straight or curved. These "smoothed" lines do not have to touch all the data points, but they should at least get close to most of them. They are called best-fit lines. In general, scientific graphs are not drawn in connect-the-dot fashon.

Here are two examples of best-fit graph lines.
One is drawn correctly, the other is not.

Best-Fit Line #1	Best-Fit Line #2

Graphs are made using:

• Paper
• Microsoft Excel

Oxygen Production Ionization Energy Hormone Levels Gas Volume Distance/Time

Plant Hormone Tree Growth Tadpole Population Clam Development Hookworms

Practice Interpreting Data:

In addition to drawing graphs, it is also important that you be able to intrepret data that is represented in graph form. The following examples are provided to help you develop the ability to read information shown on a graph.

1. Identify the graph that matches each of the following stories:
   1. I had just left home when I realized I had forgotten my books so I went back to pick them up.
   2. The battery on my electric car started to run down.
   3. Things went fine until I had a flat tire.
   4. I started out calmly, but sped up when I realized I was going to be late.
   
    

   

2. Which of the following hypotheses are best represented by this graph?
   1. Smoking causes cancer.
   2. Cancer is dangerous.
   3. One out of a thousand people will get cancer during their lifetime.
   4. Young people don't get cancer.
   5. The probability of getting cancer increases with age.
   
    
3. The graph at the right represents the typical day of a teenager. Answer these questions:
   1. What percent of the day is spent watching TV?
   2. How many hours are spent sleeping?
   3. What activity takes up the least amount of time?
   4. What activity takes up a quarter of the day?
   5. What two activities take up 50% of the day?
   6. What two activities take up 25% of the day?
   
    

4. Answer these questions about the graph at the right:

   

   1. How many sets of data are represented?
   2. On approximately what calendar date does the graph begin?
   3. In what month does the graph reach its highest point?
   
    

5. Answer these questions about the graph on the right:
   1. How many total miles did the car travel?
   2. What was the average speed of the car for the trip?
   3. Describe the motion of the car between hours 5 and 12?
   4. What direction is represented by line CD?
   5. How many miles were traveled in the first two hours of the trip?
   6. Which line represents the fastest speed?
      

   

6. Answer these questions about the graph at the right:
   1. What is the dependent variable on this graph?
   2. Does the price per bushel always increase with demand?
   3. What is the demand when the price is 5$ per bushel?
   
   

   

7. The bar graph at right represents the declared majors of freshman enrolling at a university. Answer the following questions:
   1. What is the total freshman enrollment of the college?
   2. What percent of the students are majoring in physics?
   3. How many students are majoring in economics?
   4. How many more students major in poly sci than in psych?
   
   

   

8. This graph represents the number of A's earned in a particular college algebra class. Answer the following questions:
   1. How many A's were earned during the fall and spring of 1990?
   2. How many more A's were earned in the fall of 1991 than in the spring of 1991?
   3. In which year were the most A's earned?
   4. In which semester were the most A's earned?
   5. In which semester and year were the fewest A's earned?
   
   

   

9. Using the graph at right, which of these questions is true for a family of five with a monthly income of $1000?
   1. They can afford a car payment of $200.
   2. They spend over $100 on clothes each month.
   3. They spend $50 each on food each month.
   4. They have $100 left over each month for savings.
   5. They pay $25 each month for rent.

10. Answer these questions about the graph at the right:

    

    1. How much rain fell in Mar of 1989?
    2. How much more rain fell in Feb of 1990 than in Feb of 1989?
    3. Which year had the most rainfall?
    4. What is the wettest month on the graph?

11. Answer these questions about the data table: What is the independent variable on this table? What is the dependent variable on this table? How many elements are represented on the table? Which element has the highest ionization energy? Describe the shape of the line graph that this data would produce?

Atomic Number Ionization Energy (volts) 2 24.46 4 9.28 6 11.22 8 13.55 10 21.47

12. Answer the following using the data table: How many planets are represented? How many moons are represented? Which moon has the largest mass? Which planet has a radius closest to that of Earth? How many moons are larger than the planet Pluto? Which of Jupiter's moons orbits closest to the planet? Which planet is closest to Earth?

Solar System Data Table Name Orbits Distance (000 km) Radius (km) Mass (kg) Sun 697000 1.99 x 10^30 Jupiter Sun 778000 71492 1.90 x 10^27 Saturn Sun 1429000 60268 5.69 x 10^26 Uranus Sun 2870990 25559 8.69 x 10^25 Neptune Sun 4504300 24764 1.02 x 10^26 Earth Sun 149600 6378 5.98 x 10^24 Venus Sun 108200 6052 4.87 x 10^24 Mars Sun 227940 3398 6.42 x 10^23 Ganymede Jupiter 1070 2631 1.48 x 10^23 Titan Saturn 1222 2575 1.35 x 10^23 Mercury Sun 57910 2439 3.30 x 10^23 Callisto Jupiter 1883 2400 1.08 x 10^23 Io Jupiter 422 1815 8.93 x 10^22 Moon Earth 384 1738 7.35 x 10^22 Europa Jupiter 671 1569 4.80 x 10^22 Triton Neptune 355 1353 2.14 x 10^22 Pluto Sun 5913520 1160 1.32 x 10^22

13. Use the graph at right to answer the following: Most tornadoes in Oklahoma occur between the hours of? Rounded to the nearest fifty, how many tornadoes occured in Oklahoma between 1950 and 1995? What four hour period has the fewest tornadoes?

Constructing Line Graphs