Presentation on theme: "I-N-D-E-P-E-N-D-E-N-T variables, dependent variables, and constants Catalyst: What is a hypertonic solution? Let’s say you put a cell in a hypotonic."— Presentation transcript:
I-N-D-E-P-E-N-D-E-N-T variables, dependent variables, and constants Catalyst: What is a hypertonic solution? Let’s say you put a cell in a hypotonic solution. What will happen to it?
Objectives By the end of today, SWBAT… Identify independent, dependent, and controlled variables in a scientific experiment Create a model of osmosis with eggs
Experimentation Key Point #1: A proper experiment always has an independent variable, dependent variable, and constants. The purpose of an experiment is to test how changing ONE THING affects something else.
Variables Independent Variable: The thing that I change Dependent variable: The thing that is measured Remember Variables are always nouns!!! Variables NEVER have numbers in them!!!
Good experiments… ONLY CHANGE ONE THING!!! Constant: things that we keep the same in the experiment You must keep everything but the IV constant, or your data may not be valid!
Example Let’s say we want to design an experiment to determine what causes GSP to win fights.
Determining variables from hypotheses “If Jay-Z stops cussing, he will sell fewer CDs because students like cussing.” What is the IV? “What am I changing?” What is the DV? “What am I measuring?” What are the constants? “What stays the same?”
“If Jay-Z stops cussing, he will sell fewer CDs because students like cussing.” The IV is NOT “if Jay-Z stops cussing” The DV is NOT “he will sell fewer CDs” Remember Variables are always nouns!!! Variables NEVER have numbers in them!!!
Practice You want to know if older microwaves heat food more slowly than new ones. So, you get a bunch of microwaves, write down their ages, and time how long it takes them to boil water. IV = DV = Microwave Age time to boil water
Practice You want to know which season has the most love bugs. Every night, you record how many love bugs you find outside. IV = DV = Season/month Amount of love bugs
Practice Students of different ages were given the same puzzle to assemble. The puzzle assembly time was measured. IV = DV = Age Puzzle Assembly Time
If there are more students, then there will be more school buses. IV = DV = Amount of students Number of school buses
If the cost of beignets increases, then fewer will be sold. What depends on what? IV = DV = Cost of Beignets Amount of Beignets sold
IV = Number of free agents DV = number of games won If the Saints sign more free agents, then they will win more games.
Conclusion A proper experiment always has an independent variable, dependent variable, and constants. Independent Variable: The thing that I change Dependent variable: The thing that is measured Constant: things that we keep the same in the experiment
Egg Lab! An egg is ONE cell! Underneath the shell is a semi-permeable membrane… a cell membrane! If we put this egg into a hypertonic/hypotonic solution, osmosis will occur.
Question Will an unshelled egg increase or decrease in size after being placed overnight in a hypertonic (corn syrup) or hypotonic (water) solution?
Egg lab! Read the procedures for the egg lab Fill out the hypothesis, IV, DV, and constants at the top of your egg lab worksheet Remember… Good hypotheses are testable and educated IV is what I change DV is what I measure (it depends on the IV) Constants do not change Once you have done all of this, check in with me. If you did a good job, I will let you begin the lab.
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. What is the independent variable? What is the dependent variable? What is at least one constant?
After you get your computer running… Go to this website: http://school.discoveryeducation.com/sciencefaircen tral/ http://school.discoveryeducation.com/sciencefaircen tral/ On the brown tabs on the lower left, click virtual lab. Then, hit get started. Click How Does Your Garden Grow Virtual Lab (Flash)