Designing Experiments Using the Scientific Method Lesson 1 Designing Experiments Using the Scientific Method Key Terms Scientific Method Independent Variable Hypothesis Dependent Variable Experiment Control Group Data Experimental Group Conclusion Trial Procedure Experimental Error Variable Bias Notice the color of our key terms.

process answers steps problem question organized educated guess information Identify the problem Form a Hypothesis Create an Experiment Perform an Experiment Analyze the Data Modify the Experiment Conclusion

Let’s use some of our “key words” in an investigation. I want to know if warmer temps. cause robin eggs to hatch faster? First, our procedure. (Step by step plan) Robins’ Eggs Experiment Variable Control Group Experimental Group 4 4 Number of eggs Temperature 85 degrees 97 degrees 70% 70% Humidity Lighting Low Light Low Light Variable- Factor that affects results of an experiment. There are 2 kinds of variables. 1. Independent Variable-Factor I change to find out what will happen. Here it is temp. 2. Dependent Variable-Variable affected by changes in independent variable. Here it is how long it takes the eggs to hatch. Control Group-Group used for comparison. All variables controlled by me. Experimental Group-Group exposed to changes in independent variable. Can you see what I changed in this group? Every time we repeat this experiment it is called a Trial.

Mythbusters using the Scientific Method!

scientists observations experiments hypotheses conclusions results

Why was my number different than yours!? Maybe it was experimental error? Human Error True value of measurement vs. Measured value Sunflower Seed 6 mm 7mm l___________l l___________l Your lab partner measured the same seed at 7mm. You measured 6mm. Actual measurement was 6.5 mm. Why?

But I want my hypothesis to be right! This kind of thinking can cause bias. Bias is a wish or expectation that your experiment will lead to a certain conclusion. Let’s watch a clip to better understand bias. ---------->

in a nearby pond. The farmer measures the amount of fertilizer in the Discussion Questions 1. What data would lead scientists to accept the hypothesis in the experiment with the robins’ eggs? What results might lead them to reject the hypothesis? What other variables might affect the results? 2. A farmer believes that fertilizer runoff from a farm is killing the fish in a nearby pond. The farmer measures the amount of fertilizer in the pond each week and counts the number of dead fish. The measurements indicate that, as the fertilizer concentration increases, the number of dead fish increases. Can the farmer confidently conclude that it must be fertilizer from the farm that is killing the fish? Why or why not?

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