Aim #6: What is a controlled experiment? Date: September 14, 2016 Aim #6: What is a controlled experiment? HW: Worksheet- Identifying Variables Quiz- Scientific Method next Wed/Thurs (day of double period) Do Now: Write a hypothesis about the relationship between amount of sunlight and plant height.

How do scientists solve problems? I. By utilizing the steps of the Scientific Method

Our Problem: How does our heart rate change after exercise?

Our Observations: Our observations from prior experience tell us that heart rate tends to increase after we exercise.

Our Research: Scientific Journals Library Internet Sources

Our Hypothesis: If a person does 30 Jumping Jacks, then his/her heart rate will increase.

Purpose of a controlled experiment: Remember, an experiment is done to determine the validity of our hypothesis. We are going to design an experiment that will allow us to measure heart rate after we exercise.

II. Procedure: Half the students will measure their heart rate for 1 minute during rest and write it on a piece of paper. Half the students will be instructed to complete 30 Jumping Jacks. Those students who completed the Jumping Jacks will measure their heart rate for one minute and write it on a piece of paper.

How many people should we use? III. Sample size The number of “things” included in group. VS The bigger the sample size, the better the results or conclusion will be. How many people should we use?

Controlled experiment Control group: Gets normal treatment. Experimental group: Gets the substance or the treatment you are testing. In our Exercise Experiment, which is the control group and which is the experimental group?

Constant Both groups should be treated exactly the same except for the variable. What are the constants in this experiment?

Variables Definition: factors that can change Independent (manipulated) – what the scientist controls or changes. (Ex: Exercise) Dependent (responding) – the variable that is changes because of the independent variable. (Ex: Heart Rate) what you are measuring Controlled (constant)variable – variables that are the same in each group. (Ex. Age, Exercise Type, Time of Day, etc.…)

IV. Identify the Dependent and Independent Variable: In an experiment studying the effect of sleep on student achievement. In an experiment studying the effect of caffeine on worker performance. In an experiment studying plant growth in different colors of light.

Read the following descriptions of a biology experiment Read the following descriptions of a biology experiment. Identify the control group, the dependent variable, and the independent variable. An ecologist wants to investigate the effects of pollution on soybean plants. The scientist grows five groups of plants and exposes four groups to various pollutants. The fifth group is not exposed to any pollutants. The ecologist observes the condition and growth of all the groups of plants over a period of time.

Practice Regents Questions

Base your answer to the following question on the information below and on your knowledge of biology. You are the head of the research division of the Leafy Lettuce Company. Your company is experimenting with growing lettuce using hydroponic technology. Hydroponic technology involves growing plants in containers of growth solution in a greenhouse. No soil is used. The growth solution that the company uses contains water, nitrogen, and phosphorus. The company wants to know if adding iron to this formula will improve lettuce growth.   Briefly describe how to test the effect of the formula with iron added. In your description be sure to: State a hypothesis to be tested in the new experiment. State how the control group will be treated differently from the experimental group. Identify two factors that must be kept the same in both the experimental and control groups. State what type of data should be collected to support or refute the hypothesis.

A television advertisement claims that a certain brand of cough drop reduces coughing for 8 hours. Describe an investigation that could be used to determine if this claim is valid. In your answer, include a description of: The treatment to be given to the experimental group. The treatment to be given to the control group. The data to be collected When the data should be collected One observation that would lead to the conclusion that the claim is valid.

Many people who are in favor of alternative medicine claim that large doses of vitamin C introduced into a vein speed up the healing of surgical wounds. Describe an experiment to test this hypothesis. Your answer must include at least: The difference between the experimental group of subjects and the control group. Two conditions that must be kept constant in both groups. Data that should be collected An example of experimental results that would support the hypothesis.