Scientific Method

Learning Objectives Arrange, define, and distinguish between the steps of the scientific method. Identify, define, and distinguish between independent variable, dependent variable, and control. Analyze and interpret the data collected from an experiment. Display the data collected in a table or graph. Conduct pill bug experiment. Discriminate between strong and weak sample lab reports. Compose a lab report using the lab report rubric.

Scientific Method Diagnostic Quiz The tadpoles in the cold aquarium weighed 5 grams each. The tadpoles in the room temperature aquarium weighed 7 grams each. The tadpoles in the warm aquarium weighed 6 grams each. Data Set up 3 small aquariums and place 5 tadpoles of the same species in each aquarium. In one aquarium, keep the water at room temperature. In the second aquarium, keep the water 10 degrees lower than room temperature. In the third aquarium, keep the water 10 degrees warmer than room temperature. After 3 weeks, weigh each tadpole. Test hypothesis Does water temperature affect tadpole growth? Purpose The data did not support the hypothesis because the tadpoles in the aquarium with the room temperature water weighed the most. Conclusion Most species have optimal conditions for growth. Frog mating periods vary throughout the year. Observations If the water temperature is decreased, tadpole growth will increase. Hypothesis

Scientific Method Data Conclusion Purpose Make observations State what you want to find out Make observations Use your senses and instruments Research Form a hypothesis “If ___, then ___” Test your hypothesis Experiment Data Collect Record Analyze Quantitative Qualitative Conclusion Support hypothesis Does not support hypothesis Scientists must first research and study their topic Make educated guess based on observations, should be simple with clear relationship Design an experiment that tests your hypothesis only! Don’t bring in other variables Must record all data gathered from experiment and organize it into charts, graphs, etc. Quantitative: measurements, numbers Qualitative: observations, descriptions Data will either support or not support hypothesis, does not prove anything is true or false! It’s ok if your hypothesis is not supported, that does not mean your answer is wrong Theory: Only created after numerous scientists have come to the same conclusions! Cannot be created after a single experiment.

An Example of the Scientific Method Let's say I have a problem: My car won't start. How would I use the scientific method to solve this problem? Purpose: I want my car to start. Observations: My interior lights come on when I open the door, so the battery is not the problem. My most recent gas receipt was from 10 days ago, but I usually fill up once per week. Hypothesis: If I put gas in my car, then it will start. Experiment: I will take a five-gallon gas can and fill it with five gallons of gasoline at the pump. After paying for the gasoline, I will put the gasoline in the tank. Once the gasoline is in the tank, I will attempt to restart the car. Data: The car started on the first try. Conclusion: The data supported my hypothesis. When I put gas in my car, it started. http://misterguch.brinkster.net/scientificmethod.html

Purpose: Does talking to a plant make it grow taller? Observations: Plants need CO2 to grow, we exhale CO2 when we talk Hypothesis: If a plant is talked to for one hour each day, it will grow taller than a plant that is not talked to. Test Hypothesis (Experiment): Two identical plants were placed on the same windowsill. One plant was talked to for an hour each day; the other plant was not talked to. Both received the same amount of water and light. Data: The plant that was talked to measured 16 inches tall after 30 days. The plant that was not talked to measured 10 inches tall after 30 days. Conclusion: The data supported my hypothesis because the plant that was talked to grew taller than the plant that was not talked to. What other factors could have made the plant grow taller? (errors: soil, plant differences, photoperiodism) How could you improve this experiment? (better method for CO2, more trials, more plants)

Pill Bug Experiment This will help you complete your Lab Report! Complete Scientific Method Notes 5 with your group Guidelines: You may not harm the pill bug in any way! Do not place any substance directly on the pill bug Do not submerge the pill bug in any liquid You must be able to complete the experiment in lab You can use anything in the lab room Materials provided in lab: baking soda, sugar, salt, dilute vinegar, vegetable oil, paper towels, wooden boxes, dividers After you complete your experiment (next week), complete the Data and Conclusion section on Scientific Method Notes 6 with your group This will help you complete your Lab Report!

Independent Variable This is the part of your experiment that you will test (vary) to answer your hypothesis. Should be stated after the “If” in the hypothesis This is the only thing you are changing, or varying, in your experiment. In the light bulb example… the independent variable would be the different colors of the light bulbs.

Dependent Variable This is what occurs in response to the changing independent variable. What you measure, your data. Depends on the independent variable. In the light bulb example… the dependent variable is how much the grass seeds grow (height).

Control The control should be the part of the experiment where you do not include the Independent Variable. Acts as a baseline by allowing you to compare your results in the experiment. In the light bulb example… the control is the pot with grass seeds that are growing under the white light bulb. No independent variable is present in the control.

Does playing video games affect a person’s heart rate? Average heart rate of the person while at rest, before playing video games Control (independent variable is absent) Playing video games Independent variable Average heart rate of the person after playing video games Dependent variable

Does color affect taste preference? Independent Variable: Beer that is dyed different colors Dependent Variable: Taster’s preference Control: Glass of beer with no dye (independent variable is absent)

How to use the lab report grading rubric Read each component carefully while composing your lab report. Refer to example lab reports on Campus Cruiser. Your lab report will be graded by evaluating each component in your paper. For example: If your Purpose contains the criteria stated in the “B” column, you will receive 8.5 points towards your total points. Self-check: Grade yourself using the rubric to see which components need revision.