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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

CLAIMPlants grow best when placed in red light.

EVIDENCEAs 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

REASONINGBecause 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 statement2. 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) 0 10 20 30 40 50 60 70# of bubbles 0 3 7 12 7 4 1 0