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Biology Notes: Graphing Alabama Biology Course of Study Objective #1 Glencoe High School Mrs. Meredith Barkley Vocabulary List (Graphing) Data Unit Quantitative Measurement Qualitative Measurement Data Table Column Header Ordered Pairs Horizontal Axis Vertical Axis Title Constant Variable Line Graph Pie Graph Students will need a basic understand of the meaning of each term in order to develop the skill of organizing and interpreting data, which is ESSENTIAL for scoring well on the science portion of the ACT. These terms will be covered within class discussions and activities. Table of Contents (Graphing) 1. 2. 3. 4. 5. 6. What is data? How should you collect data? Why is graphing so important? Which type of graph should I use? How do I interpret data for potential relationships? Graphing Checklist 1. What is Data? Data = information This may in the form of pictures, recordings, collections, drawing, and notes…but most of the time will be a big pile of numbers! Data may provides you with… 1. 2. Quantitative Measurements: numerical information, such as height, temperature, and mass Qualitative Measurements: descriptive information, such as color, texture, smell, taste, appearance 2. How should you collect data? You must always collect measurements using appropriate instruments. For example, you may use a beam balance to calculate mass, or a graduated cylinder to calculate liquid volume. Remember to use metric units in science class unless told otherwise. For example, you should measure length in its metric unit, the meter, as opposed to feet, which you may be more familiar with. 3. Why is graphing so important? What’s the big deal? Oh, nothing really… Graphing just makes life easier and decision-making a little quicker! There are 2 basic reasons you should learn how to construct data tables and graphs outlined below. 1. Organization 2. Interpretation… People may use data tables and graphs to monitor someone’s vital signs at a hospital, make decisions about which products to sell for their company, analyze the correlation between consumption of certain foods with various health concerns, or designing a new wing design for an airplane! Remember (as previously stated) the importance that interpreting data can have on your score on the science portion of the ACT. 4. Which type of graph should you use? You may encounter pie graphs, line graphs, bar graphs, pictographs, and multiple line graphs within class. While each situation may be a little different, there are a few basic rules you can apply when choosing the correct graph to construct from your data. Pie graphs should be used to represent data in the form of percentages. A line graph should be used to show the change of an item over time. A bar graph should be used to compare various items by the same criteria. A multiple line graph can be used to compare how two different factors changed over the course of the same experiment. 5. How do I interpret a graph for potential relationships? When the two variables are said to be “directly proportional” that means that they will both increase together or both decrease together. This will be represented visually by a data that increases (upward slope) from left to right. When two variables are said to be “inversely proportional” that means that as one increases that the other will decrease and vice versa. This will be represented visually by data that decreases (downward slope) from left to right. Other times, there seems to be no connection between two variables and no relationship is identified. Remember, these rules only apply if someone has correctly placed the constant (independent variable) on the x-axis and the variable (dependent variable) on the y-axis! One More Time…How do I interpret a graph for potential relationships? Directly Proportional Data Inversely Proportional Data Both increase or both As one increases, the other decrease decreases and vice versa OR Practice Problems: Interpreting Data / Identifying Relationships 1. What type of relationships, if any, do the following have in common? 2. How would you label the x and y axis for each situation? Size of a diaper vs. total # that can fit in a trash bag # of absences in school vs. report card grades Amount of sweets consumed vs. total body weight Level of education vs. income Drug use vs. # of criminal arrests # of family members who smoke vs. percent chance you will also become a smoker Graphing Checklist Always include the following when appropriate: Title Neat x and y-axis Even increments on both x and y-axis Label on both x and y-axis Units of measurement places in parenthesis Accurate Data Key Remember, the dependent variable belongs on the y-axis, while the constant / independent variable belongs on the x-axis.