What is an Experiment? An organized procedure for testing a hypothesis Good experiments produce accurate (reproducible) results Good experiments are easily re-done; followed by someone else

The Problem You are working at a movie theater and the manager approaches you complaining about the amount of un-popped popcorn kernels. She complains that the theater is loosing money because of wasted, un-popped popcorn. Design an experiment to solve the problem. HINT: Popcorn is thought to pop better if stored at cold temperatures!!

Parts of an Experiment Any good scientific experiment needs a CONTROL; something used for comparison Conclusions can not be made without a control The control shows that the experimental results are related to the defined problem (what you are testing) Ex: If you hypothesize that the popcorn will pop better after being stored in the freezer, you must also test how it pops after being stored at room temperature. This is your comparison or control. Control: Popcorn stored at room temperature

Parts of an Experiment Scientific experiments also have CONSTANTS CONSTANTS are factors that don’t change during an experiment Constants allow you to test one variable at a time Constants help ensure accurate results!! You want to keep as many things constant as possible Ex: Brand of popcorn, popping conditions,storage time, etc. must be constant!!

Parts of an Experiment Good scientific experiments have ONE independent variable Independent Variable – what you are testing: you purposely change this during the experiment Ex: Effect of storage temperature on the popcorn**

Parts of an Experiment Good scientific experiments have at least one Dependent Variable Dependent Variable: changes because of the independent variable; depends on the independent variable Ex: Number of un-popped popcorn kernels

Parts of a Scientific Experiment Control: Used as a comparison; validates results Ex: Popcorn stored at room temp. Constants: things that are purposely kept the same during the experiment; validates the cause Ex:Brand of popcorn, time stored, popping conditions, etc. Independent Variable: the thing being tested and purposely changed during the experiment; should only be one thing! Ex: Storage temperature Dependent Variable: the thing that changes because of the independent variable (depends on the independent variable) Ex: Amount of un-popped kernels

The Data Data – information gathered during an experiment Data can be qualitative (descriptive) or quantitative Descriptive data – comes from your senses; what you see, smell, feel, hear, or taste. Quantitative data – recorded as numbers or values – comes from measurements, weight, temperature, calculations, etc. Scientific experiments often use both types of data!