Question

in this lesson, you learned about line, bar and circle graphs. you learned how to read and interpret information from each type of graph, and how to construct these graphs. if you were asked to create a graph from a given set of data, how would you know which type of graph to use? which graph you choose depends on the type of data given and what you are asked to convey to the reader.
instructions:

1. read the information below and determine which type of graph to use. be prepared to justify your choice.
2. draw your graph on a whiteboard.
3. be prepared to discuss experiment variables and conclusion.

a student studied the effect of gibberellin (a plant hormone) on the growth of corn seedlings of the same height and species. a different concentration of gibberellin in a fixed volume of water was applied to 7 groups of 10 plants each maintained under the same environmental conditions for the duration of the experiment. at the end of this period, the height of each plant was measured. the data is shown in the table to the right.
data table

micrograms of gibberellin in a water solution	average height (cm)
0.05	40
0.10	60
0.25	70
0.50	75
1.00	80
2.00	80

each year, a new york state power agency provides its customers with information about some of the fuel sources used in generating electricity. the table below applies to the period of 2002 - 2003.
fuel sources used

fuel source	percentage of electricity generated
coal	5
nuclear	4
oil	1
solar	4

tooth decay occurs when bacteria living in the mouth produce an acid that dissolves tooth enamel (the outer, protective covering of a tooth). a recent survey in different continents provided the following results.
the effect of sugar intake on tooth decay

world regions	average sugar intake per person (kg/year)	average number of teeth with decay per person
africa	18	1.7
southeast asia	14	1.6
europe	36	2.6

Explanation:

Step1: Analyze data - Gibberellin and plant growth

The data shows a relationship between the concentration of a plant - hormone (gibberellin) and the average height of corn seedlings. A line graph would be ideal as it can clearly show the trend of how the average height changes with the increase in gibberellin concentration.

Step2: Analyze data - Fuel sources for electricity

The data represents the percentage of electricity generated from different fuel sources. A pie - chart (circle graph) would be best here as it can effectively show the proportion of each fuel source to the whole in terms of electricity generation.

Step3: Analyze data - Sugar intake and tooth decay

The data compares the average sugar intake and the average number of decayed teeth across different world regions. A bar graph would be suitable as it can easily compare the values for each region for both variables (sugar intake and number of decayed teeth).

Answer:

1. For the effect of gibberellin on the growth of corn seedlings: Line graph.
2. For the fuel sources used in generating electricity: Pie - chart (circle graph).
3. For the effect of sugar intake on tooth decay: Bar graph.