Scientific Method- Experimental Investigation

Problem Pose a question. Clearly state a problem of study. Include specimen used, manipulated variable that will be studied and changed, purpose of the study, and time (duration) of your project. Which temperature (10oC or 30oC) is better for zinnias to continue producing flowers for 5 months?

Hypothesis Use “If, then, because” format. If temperatures of 10oC and 30oC are used on zinnias to study which temperature will allow for better production of flowers for 5 months, then 10oC will be best because the plants would have a better chance to grow deeper roots for absorption of water by the time summer temperatures and dry weather set in. The 30oC plants will have limited root growth because of the temperatures drying out water for transport into roots.

Hypothesis The “If” part rephrases the problem. The “then” part gives the prediction. The “because” part gives a biological or chemical explanation for the prediction.

Summary of Lab Design Variables Identify the manipulated variable, with the range used. This is introduced to the specimen to see what change will occur when compared to the control. Be clear. The manipulated variable is the independent variable. Describe the control of the experiment. Give complete sentences. Describe three constant factors used in the experiment. Give complete sentences.

Examples of the Lab Design Identify the manipulated variable: The manipulated variable in the study is temperature. The range of the manipulated variable temperature is 10oC and 30oC. Notice that the control is not part of this variable. Describe the control: The control is the zinnia plants exposed to 20oC for 5 months. Notice how an organism used or the subject is always stated. Describe three constant factors. The constant factors are: using the same type of zinnia seeds- Thumbelina; planting the zinnia seeds at the same depth in the ground- 1cm; and planting the same number of zinnia seeds for each temp.- 10 seeds

Materials List materials used. Bullet materials going down. Example: Beaker Ruler Hot plate

Procedure Identify the manipulated variable procedure section. List the steps of the procedure in order of performance. Use numbers to identify each step. Identify the control procedure section. Include a large sample size or repeat trials of study. Include what data you will measure. Include how you will measure data and units used. Include how long the study will be. Include the type of math that will be used to analyze results.

What to include in both procedure sections- Manip. Variable and Control Include the sample size. A large sample size or number of repeated trials is to appear in both procedure sections.. Include what data you will measure in each procedure section. Give units of measurement. Include how you will measure data in each procedure section. Include how long the study will be for both. Include the type of math that will be used to analyze results for both sections..

Example for Writing a Procedure Manipulated Variable Procedure 1. 2. 3. Control Procedure

Qualitative Observations Write out qualitative observations in complete sentences. Observations are written in a paragraph or paragraphs. Avoid inferences.

Quantitative Date: Chart and Graphs Present numerical data in a chart. Title the chart to describe what it is being shown. Clearly label all columns and rows. Have units identified. Title the graph to describe what it is being shown. Clearly label each axes. Produce the correct type of graph.

Example of a Chart Average Growth of Zinnias When Exposed to 10OC For 1 Month Plant Number Mean Growth (cm) 1 6 2 7 3 5.2 4 6.3 5 6.9 6.5 8 9 10 6.6

Example of a Graph

Analysis How did the manipulated variable affect the purpose of the experiment? Give evidence to support how the manipulated variable affected the experiment. To do this, use statistics from the data collected by calculating means, rates of change, percentage, etc… Compare the manipulated variable results to control results. Give biological explanations to the data collected. Explain any source of error.

Example of a Beginning Analysis At 30oC, zinnia plants grew less than the other temperatures and produced less flowers. At 10oC, an average rate of 6.2 mm in height/day occurred compared to 4 mm/day at 30oC. Though seeds planted germinated at the 3 temperatures used in this experiment, the 20oC plants were exposed to a more favorable temperature with 9.7 mm/day that allowed for better root growth in the soil…

Identify Sources of Error Identify and explain the source of error(s). Some of the seeds never germinated. This was due to lack of water needed to stimulate germination. Without water, seeds would never become activated to go through chemical changes such as for the digestion of starch to produce glucose needed as a source of energy for growth.

Conclusion Was the hypothesis supported by the data?

Example of a Conclusion The hypothesis was supported by the data collected in this experiment or use the hypothesis was not supported by the data collected in this experiment. The hypothesis is never stated to be true, correct, or wrong.

References List all references used by you. References that cannot be used are: The biology textbook Books/references older than 2005 Wikipedia, encyclopedias, dictionary, eHOW, ASK.com Ramos, Nancy. Lighthouse Bridges. San Antonio: My Publishing Co., 2006 (this is an example, it is not real)