HONORS LIVING ENVIRONMENT MS. ETRI TOPIC 1: THE SCIENCE OF BIOLOGY AND SCIENTIFIC INQUIRY PART 3: HOW SCIENTISTS TEST HYPOTHESES--DESIGNING CONTROLLED EXPERIMENTS WHAT IS A CONTROLLED EXPERIMENT? ____________________________________________________________________________________ ____________________________________________________________________________________ PARTS OF AN EXPERIMENT CONSTANTS: factors that are kept the same in an experiment and are not allowed to change. VARIABLES: factors in an experiment that can change. Ex: equipment used, type of material, amount of material, temperature, light and time. I. INDEPENDENT VARIABLE (____________________ VARIABLE): ________________________ _______________________________________________________________________________ II. Can have different levels (ex. Temperature can be cold, warm hot; amount of substance can be low, medium, high). Whatever you are testing is the independent variable. “I” change it. DEPENDENT VARIABLE (______________________ VARIABLE): ________________________ _______________________________________________________________________________ It is the part of the experiment we are trying to measure (our data!) EXPERIMENTAL GROUP (TEST GROUP): the 1 HONORS LIVING ENVIRONMENT group in an experiment that receives the variable being tested. MS. ETRI CONTROL GROUP: the group in an experiment ___________________________________ OR receives a _________________________ instead. It is the part of the experiment that serves as the _______________________________________. Why is it necessary? It is the unchanged part of the experiment that detects the effects of hidden variables. PLACEBO: ___________________________________________ used as a control in an experiment (to determine the effectiveness of a medicinal drug). o Ex. ______________________________ *Ideally, a control group and an experimental group differ only in the one variable the experiment is designed to test. Monkey See, Monkey Take Monkeys have a working notion of other minds. https://www.youtube.com/watch?v=VbQf6X9UkX0 INDEPENDENT VARIABLE:___________________________ DEPENDENT VARIABLE:_____________________________ CONSTANTS: ______________________________________ WHAT MAKES AN EXPERIMENT MORE VALID? Large sample size. Multiple, repeated trials. o Increasing the number of times that a level of the independent variable is tested. Having a control group. Having significant differences between results obtained from control group vs. results obtained by the experimental group(s). Exercise: In the following examples, tell which group is the control group and which is/are the experimental group(s) based on the given scenarios. 2 HONORS LIVING ENVIRONMENT MS. ETRI 1. In an experiment to test the effectiveness of Tylenol Cold on patients with a cold virus, a scientist set up two groups. One group was treated with 500mg of Tylenol Cold and the other group was given a 500mg sugar pill. After 5 days of treatment, the patients' cold symptoms were evaluated. Control Group: ___________________________________________________ Experimental Group: ______________________________________________ Independent Variable: ______________________________________________ Dependent Variable: _______________________________________________ 2. A researcher is curious to find out what effect classical music has on people’s level of relaxation (as measured by heart rate). He suspects that listening to classical music will make people feel more calm and relaxed. He lets one group listen to classical music for one hour. He lets another group sit in a quiet room for one hour (i.e they hear no music). After one hour, he monitors the heart rate of each participant to measure their level of relaxation. Control Group: ____________________________________________________ Experimental Group: _______________________________________________ Independent Variable: ______________________________________________ Dependent Variable: _______________________________________________ 3. A researcher conducts an experiment to assess the effects of alcohol on people's sense of balance. He divides his subjects into three groups: in one group the participants drink one ounce of alcohol, in another they drink two ounces of alcohol and in a third group the participants drink soda. He then watches as each participant tries to walk on a straight line from one corner of the room to the next and notes how many times they stumble outside the line. Control Group: ____________________________________________________ Experimental Groups: ______________________________________________ Independent Variable: _______________________________________________ Dependent Variable: ________________________________________________ Example: Identify the constants in the following experiment: 4. Cleo created a secret ingredient for a breath mint that she thinks will "cure" the bad breath dogs get from eating table food. She asked 100 female German Shepherds with a history of bad breath to try her new breath mint. She had 50 female German Shepherds (Group A) eat a breath mint immediately after they finished eating 5 leftover chicken wings. The other 50 female German Shepherds (Group B) received a regular store bought brand of breath mints immediately after they finished eating 5 leftover chicken wings. The store bought brand did not contain Cleo's secret ingredient, although both groups were told that they were getting the breath mint that would cure their bad breath. Two hours after eating the chicken wings, 30 dogs in Group A and 10 dogs in Group B reported having better breath than they normally had after eating leftover chicken wings. Constants 1. __________________________________ 2. ___________________________________ 3 HONORS LIVING ENVIRONMENT 3. ___________________________________ 4. ___________________________________ MS. ETRI DESIGNING YOUR OWN CONTROLLED EXPERIMENT **PLEASE COMPLETE ON A SEPARATE SHEET OF PAPER** On a television talk show, a guest claims that people who exercise vigorously for 15 minutes or more every day are able to solve math problems more rapidly than people who have no vigorous exercise in their daily routine. Design a controlled experiment that could be conducted to test this claim. Give possible results from your experiment. After you have designed your experiment. Answer the following: State the purpose of the experiment State why the sample to be used should be large Describe how the experimental group will be treated and how the control group will be treated. Identify the constants, independent variable, and dependent variable. State the specific data to be collected during the experiment Create your own data table (with “fake” data). Don’t forget to label! State one way to determine if the results support the claim. 4 HONORS LIVING ENVIRONMENT MS. ETRI 5
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