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Catalyst – January (42 + 3), 2009 1. 2. 3. What question is this data table answering? What is one conclusion we can make from looking at this data table? Write a hypothesis to answer this question: Why is hydro (water) power used so greatly? Write in complete sentences! Don’t talk during the Catalyst! Today’s Agenda Catalyst Variables Notes and Practice Time I-N-D-E-P-E-N-D-E-N-T! DEPENDENT CONSTANTS Exit Question HOMEWORK TONIGHT! QUIZ ON THURSDAY! GUEST SPEAKER ON FRIDAY! Today’s Objectives SWBAT identify independent, dependent, and constant variables in a scientific experiment. Experimentation Key Point #1: A proper experiment always has an independent variable and dependent variable. The purpose of an experiment is to test how changing ONE THING affects something else. Variables Independent Variable: what causes the change we are measuring (acts independently) Dependent variable: what gets changed (depends on other things) Remember Variables are always CATEGORIES of things: time, amount, frequency, size, type Variables are NEVER specific things!!! Demo http://www.unitedstreaming.com/ videos/dsc/externalApplications/ virtual_labs-es/Plants/index.html Teacher Models Scientists have discovered something shocking: if you eat a lot of candy, then you will gain fat. What is the independent variable? A. B. C. D. Eat a lot of candy Type of candy you eat Amount of candy you eat How much weight you gain Teacher Models Happy students learn more in school. So, Ms. Stroh believes that starting school later would increase test scores. What is the dependent variable? A. B. C. D. Starting school later Happy students Time that school starts Test scores NEW PROCEDURE! WHITEBOARDS! Whiteboard Practice When Ms. Stroh says “GO!” Send one member of your group to get whiteboards and markers for everyone (back lab bench) Send up another member of your group to get napkins for everyone (green bin) Hurry! Remember, we want to stay under 3 minutes of transition time! Whiteboards 1 Ms. Stroh believes that the more you study, the better grades you’ll earn. What is the independent variable? A. B. C. D. Studying more Amount of time you study Grade earned Type of test Whiteboards 2 Shanel is always cold in class. She hypothesizes that if she wears many layers of clothing to school, then she will be warmer. What is the dependent variable? A. B. C. D. Number of layers Shanel wears How cold Shanel is Temperature of the room Shanel will be warmer Whiteboards 3 Ms. Stroh’s students want to test how easily bought off he is. Students who give him an apple get a “C.” Students who give him candy get an “A.” What is the independent variable? A. B. C. D. Type of food Apples and candy “A” on the report card Report card Whiteboards 4 Jenika hates running, but loves listening to music. She believes that if she listens to music while running, then she will run more often. What is the dependent variable? A. B. C. D. She will run more often Listens to music while running Frequency that Jenika runs What Jenika listens to If you’re having trouble… WRONG 4 minutes 26 mg of baking soda Lifting weights every day Medium t-shirts Bullfrog 16 candles Never gets sick RIGHT Time to get dressed Amount of baking soda Frequency of lifting weights Size of t-shirts Type of frog Number of candles Degree of health Review Ms. Stroh believes that the more you study, the better grades you’ll earn. What is the independent variable? A. B. C. D. Studying more Amount of time you study Grade earned Type of test Review Shanel is always cold in class. She hypothesizes that if she wears many layers of clothing to school, then she will be warmer. What is the dependent variable? A. B. C. D. Number of layers Shanel wears How cold Shanel is Temperature of the room Shanel will be warmer Review Ms. Stroh’s students want to test how easily bought off he is. Students who give him an apple get a “C.” Students who give him candy get an “A.” What is the independent variable? A. B. C. D. Type of food Apples and candy “A” on the report card Report card Review Jenika hates running, but loves listening to music. She believes that if she listens to music while running, then she will run more often. What is the dependent variable? A. B. C. D. She will run more often Listens to music while running Frequency that Jenika runs What Jenika listens to Guided Practice Worksheet 8 minutes to complete 3 minutes to compare answers KEEP THIS to help you with homework tonight Constants Key Point #2: Everything but the independent and dependent variable must be kept constant. Constant: If variable we keep the same many different things change at once, we don’t know what causes the change! Example Let’s say we want to design an experiment to determine what causes GSP to win fights. Number of fights that GSP wins Answer in notes Jay-Z hypothesizes that if he stops cussing, then he will sell fewer CDs because students like cussing. What is the IV? What is the DV? What are the constants? Remember, variables are CATEGORIES. If [Jay-Z] stops cussing, then he will sell fewer CDs because students like cussing. IV Frequency that Jay-Z cusses How often Jay-Z cusses Amount of curse words in Jay-Z songs DV Number of CDs Jay-Z sells How many CDs Jay-Z sells Constant Amount of money CDs cost Number of tracks on each CD How good each CD is Practice You want to know when in the year there are the most love bugs. Every night, you record how many love bugs you find outside. IV = Time of year (season/month) DV = Amount of love bugs Constant = Practice Jenika needs to run a 6 minute mile to pass PE. She believes that if she runs every day, then she will be able to run faster. IV = Frequency that Jenika runs DV = Mile time Constant = Practice Students of different genders were given the same puzzle to assemble. The puzzle assembly time was measured. IV = Type of gender DV = Time to assemble puzzle Constant = If there are more students, then there will be more school buses. IV = Amount of students DV = Number of school buses Constant = What depends on what? IV = DV = Amount each beignet costs Number of beignets sold Constant = If the cost of beignets increases, then fewer will be sold. If the Saints sign more free agents, then they will win more games. IV = Number of free agents DV = Number of games won Constant = Conclusion A proper experiment always has an independent variable and dependent variable. Everything but the independent and dependent variable must be kept constant. Independent Variable: what causes the change we are measuring Dependent variable: what gets changed Constant: variable we keep the same Exit Question Let’s say you want to figure out if drinking milk actually makes you taller. So you drink a glass of milk every day, and record your height every day. 1. 2. 3. What is the independent variable? What is the dependent variable? What are at least two constants? Write in complete sentences! Don’t talk during the Exit Question!