ISCI 2002 Physical Science for Teachers Scientific Method ISCI 2002 Physical Science for Teachers

What is the Scientific Method? Series of Steps? Scientist use different approaches; different types of evaluations Steps used by most Observation of nature Explanation of what is observed Explanations used to make predictions Test predictions Modify explanation No set order or routine

Formulation of a Hypothesis An “educated guess” based on previous research or experimentation. Explanation (experiment derived explanation) “Tentative” Must be tested. May be accepted or rejected Universal hypothesis statement As the independent variable (increases, decreases) the dependent variable will (increase, decrease) Variables Independent vs dependent

Testing the Hypothesis Simple Hypothesis: “birds build nests in tree cavities” Observe and record More complex devise an experiment Production of a ‘song’ by a bird Many variables involved (nervous and muscular systems; environmental factors) Try and understand the (of the previous variables) roles of the factors in the production of a song.

Control vs. Experimental Tests Controlled experimental set-up Compares two situations that have identical factors except for one that differs Controlled group All factors are the same Experimental set-up One factor or variable is changed and observed

Bird Song Example Simple questions are formulated (deals with each variable or factor involved) Muscles; nervous system; hormones; climate; etc. How do male sex hormones stimulate male birds to sing? Experimental group: male bird testes removed Controlled group: testes remain in tact Look to see if there is a relationship between the groups or not (did removing the testes affect the birds ability to sing?)

Collecting Data Displayed in table, charts, etc. Time Growth in Height (cm) Day 1 2.5 cm Day 2 4.5 cm Day 3 6.5 cm Day 4 8.5 cm Day 5 10. 5 cm

Analyzing Data Analyzing Charts Graphs Statistics Was there a relationship between the variables? Direct Indirect None observed Quantitative and Qualitative

Graphing Data Time (days)

Graphical Analysis Rate or Slope = rise/run Rate = Y2-Y1/X2-X1 Calculating the rate or ‘slope’ Rate or Slope = rise/run Rate = Y2-Y1/X2-X1

Graphing Data Time (days)

Conclusion(s) Based on the analysis of the data was the hypothesis accepted or rejected? Recommendations for retesting? Modifications?