Scientific Method - steps 1. State the problem 2. Form a hypothesis 3. Design an experiment 4. Evaluate the hypothesis 5. Repeat for accuracy

State the problem/Title What do we want to know? Can be a question Form a hypothesis Must be testable Needs to make a prediction Format “If ……. then……. If – what is being tested – Independent variable Then – predict what will happen – Dependent variable

Design an Experiment List of materials Safety precautions Variables what you measure in an experiment dependent variable Data or results What is being measured Y-axis independent variable “If”; “I” change What is being manipulated by the experimenter X-axis

Design an Experiment Step by step procedure 2 groups – Experimental group – gets the Independent variable (ONLY 1!!!) – the factor being tested – “I” change or manipulate Control group - for comparison – does NOT get the independent variable – gets a placebo Constants – NOT the control – things to be kept the same between all the groups Data table – to record results/data – the Dependent variable – 2 types Quantitative – can be measured Qualitative – is descriptive

Design an Experiment Organize your data Analyze your data Allows you to see trends and patterns more easily (graphs) Analyze your data Does the data have meaning? Is there a significant difference in the results between the control and the experimental group? Sources of error – NOT mistakes Factors you couldn’t or didn’t control for

How’s a critter to choose? Graphs line graphs graphing data that shows continuous change bar graphs (or histograms) graphing data that is in disconnected groups How’s a critter to choose? 2005-2006

elevation (feet above sea level) How does elevation affect temperature? Line graph! elevation (feet above sea level) temp. (°C) 30 500 25 1000 20 1500 15 2000 10 2500 5 30 25 20 18 temperature 15 10 1200 ft? 5 500 1000 1200 1500 2000 2500 2005-2006 elevation

Which drink do you like best? number Coke 1 Pepsi Water 4 Iced tea Gatorade 3 6 Bar graph! 5 4 number of students 3 Red Bull? 2 1 Coke RB Pepsi RB water tea Gatorade 2005-2006 type of drink 8

Evaluate the Results - Conclusion Data does NOT support hypothesis – there was no significant difference OR you got unexpected results → Doesn’t mean you did it wrong Revise hypothesis and experiment as necessary and try again

Evaluate the Results - Conclusion Data supports hypothesis – you got the results you expected → Repeat, Repeat, Repeat!!! If of scientific value – publish so others can repeat, repeat, repeat If supported again and again → THEORY FACTS can be proven LAWS are known to be true, but may not be explainable (ex – gravity)

Examples of experiments 1 How does fertilizer affect the growth rate of plants? we set up an experiment testing different amounts of fertilizer on different plants & measuring the growth (height) of the plants: dependent variable (Y-axis)? height of plants independent variable (X-axis)? amount of fertilizer The effect of _____________ on _____________ Amount of Fertilizer Height of Plants 2005-2006