# Designing Experiments Using the Scientific Method

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Designing Experiments Using the Scientific Method
Lesson 1 Designing Experiments Using the Scientific Method Key Words 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 words.

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) Variable Control Group Experimental Group Number of eggs 4 4 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. *Independent Variable-Factor I change to find out what will happen. Temperature *Dependent Variable- Variable affected by changes in independent variable. 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.

Do cows cause global warming?

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.

scientists observations experiments hypotheses conclusions results

The Bikini Bottom gang loves science class and wants to do a little research. Read the description for each experiment and use your knowledge of the scientific method to answer the following questions.

Flower Power SpongeBob loves to garden and wants to grow lots of pink flowers for his pal Sandy. He bought a special Flower Power fertilizer to see if it will help the plants produce more flowers. He plants 2 plants of the same size in separate containers with the same amount of potting soil. He places one plant in a sunny window and waters it every day with fertilized water. He places the other plant on a shelf in a closet and waters it with plain water every day. What did SpongeBob do wrong in this experiment? Explain. How can he test the effectiveness of the fertilizer? Set up an experiment that tests this .

Super Snails Snail Before After Gary 64% 80% Larry 78% Barry 82% 84%
Gary is not the smartest snail in Bikini Bottom and believes he can improve his brain power by eating Super Snail Snacks. In order to test this hypothesis, he recruits SpongeBob and several snail buddies to help him with an experiment. The snails eat one snack with each meal every day for three weeks. SpongeBob created a test and gave it to the snails before they started eating the snacks as well as after three weeks. Snail Before After Gary 64% 80% Larry 78% Barry 82% 84% Terry 72% 70% Based on the data, do the Super Snail Snack work? Explain. Set up the experiment and list the procedure he should use.

Bubble Time Patrick loves bubble gum and would like to be able to blow bigger bubbles than anyone else in Bikini Bottom. To prepare for the Bikini Bottom Big Bubble Contest, he bought five different brands of bubble gum and he needs your help to find the brand that creates the biggest bubbles. Write an experiment to test the bubble power of the bubble gum brands and help Patrick win the contest.

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? Using the data table in our notes, write out the procedures that should be included in this experiment.

A farmer believes that fertilizer runoff from a farm is killing the fish in a nearby pond.
1. Set up an experiment to test his hypothesis. Be sure to include all the procedures he needs to follow. 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. 2. 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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