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HYPOTHESIS AND VARIABLES Step 3: Form a Hypothesis Hypothesis- a testable explanation of an observation. A hypothesis is NOT just an educated guess about what you think will happen. It must be able to be tested! Step 3: Form a Hypothesis We write the hypothesis in an If-Then statement ex: If the amount of fertilizer is increased, then the height of the plant will increase. Variables & Controls A variable is anything that changes in a scientific experiment. The control is what you use to compare the results to in the end of the experiment. There are 2 types of variables: Independent Dependent Step 3: Form a Hypothesis The Independent Variable goes after the “If” I.V. If the amount of fertilizer is increased, then the height of the plant will increase. Step 3: Form a Hypothesis The Dependent Variable goes after the “Then” If the amount of fertilizer is increased, then the height of the plant will increase. D.V. Now You Try: If you spend more time studying, then your grade will improve. Independent Variable = Dependent Variable = Now You Try: If you spend more time studying, then your grade will improve. Independent Variable = amount of time spent studying Dependent Variable = grade Now You Try: If the temperature of the room is increased, then the bacteria will grow faster. Independent Variable = Dependent Variable = Now You Try: If the temperature of the room is increased, then the bacteria will grow faster. Independent Variable = temperature of room Dependent Variable = bacterial growth Variables & Controls A variable is anything that changes in a scientific experiment. The control is what you use to compare the results to in the end of the experiment. 2 Types of variables: Independent Variable: What you change. Dependent Variable: What changes because of the Independent Variable. 2 Types of variables: Independent Variable: Cause Dependent Variable: Effect Independent Variable Independent Variable: What you change. Cause a.k.a Manipulated Variable Graphed on x axis Dependent Variable Dependent Variable: What changes because of the Independent Variable. Effect a.k.a Responding Variable Graphed on y axis Independent Variable vs. Dependent Variable Independent Variable Also Known As: Manipulated Variable Dependent Variable Responding Variable Results: Cause Effect On a graph: X axis Y axis After all of the data from the experiment is collected, then its time to organize the data. Step 6: Organize your data Put your data into a data table Independent Variable __________(unit) Levels Dependent Variable _______________ (unit) Trial 1 Trail 2 Trail 3 mean range Step 6: Organize your data Make the data table into a graph GRAPHS make it EASIER to see patterns in the data! Step 6: Organize your data How do you know what goes on each axis of the graph? Step 6: Organize your data DRY MIX Dependent Variable = Responding Variable = Y axis Manipulated Variable = Independent Variable = X axis Parts of a graph Y Axis X Axis Parts of a graph Y Axis (Dependent Variable) X Axis (Independent Variable) DRY MIX Dependent Variable Graphing: Independent Variable Any Questions????