Do Now  List the steps of the SCIENTIFIC METHOD

The Nature of Science The Scientific Method & Experimental Design

Step 1:Problem Statement/Purpose EX: What is the effect of different colored lights on plant growth?

Step 2: Research  EX: Research plant growth or the best conditions for plant growth

Step 3: State your Hypothesis  EX: If 3 plants are grown under green, red and blue light, then the plant under blues light will grow the most in the same period of time.

Step 4:Test  Run an experiment

Step 5: Collect and Analyze data Quantitative data Qualitative data EX: measure the growth of the plants in meters; describe the color of the leaves

Step 5 cont’d: Analyzing data  charts  tables  graphs

Step 6: Draw a conclusion  CLAIM Plants grow best when placed in red light.  EVIDENCE As shown in the data, the plants in green light grew and average of 1cm, the plants in blue light grew an average of 4 cm, and the plants in red light grew an average of 10 cm. In comparison, the plants in sunlight grew an average of 11cm  REASONING Because plant pigments absorb all colors but green, the plants in green light did not absorb light for photosynthesis. The plants in the red light grew the most because…

The Nature of Science Designing an experiment

Manipulated variable  In a controlled experiment only one variable is changed, or manipulated Independent variable is the variable in an experiment that is causing a change

Responding variable  The dependent variable is what is changed by the manipulated variable  It is what is being measured or observed

Constants  Variables in an experiment that stay the same

Experimental & Control Groups  Experimental group The individuals or groups being tested on  Control group The individuals or groups in which the variable is not changed; the normal group

Graphing variables  When graphing, the independent variable always goes on the X-axis If IV is qualitative (words)  bar If IV is quantitative (numbers)  line (if over time) or scatter plot The dependent variable always goes on the Y-axis

Graphing Practice (from an AP bio exam!)  You want to find out what temperature is the best for yeast respiration. Yeast cells are placed in a sugar solution. The temperature is varied and the number of bubbles of gas released is recorded 1.problem statement 2.hypothesis

Data  Copy the following chart:  3. IV = DV =  4. Graph the results.  5. Determine the optimum (best) temperature for respiration in yeast. How do you know? Temperature (C) # of bubbles