Scientific Method

OVERVIEW

What is the Scientific Method? It’s a way to solve/explain a problem or natural phenomenon, while removing human bias and opinion. It is a critical procedure that allows validity and consistency in the science field.

The steps of the Scientific Method are: Observe/form a question Gather Information/Research Hypothesis Experimentation Analyze data Conclusion

INTRODUCTION

Observe/Form a question What do we observe? – We can observe anything in nature.

Gather Information Why is it important to gather information on the topic you are looking into? – Science is always trying to grow in understanding. As a scientist, you want to be testing something new, not just redoing experiments that have already been done.

Gather Information Where do you look for information? – It is very important that you look in the right places when gathering information. You want to find peer reviewed articles published by trustworthy journals to guarantee their accuracy.

Hypothesis A hypothesis is a tentative testable explanation. A hypothesis should be written as an “If…then statement” A hypothesis should be written in such a way that the experimental variables are identified. “If the independent variable is changed in some way, then the dependent variable will change in this way.”

Hypothesis Melissa raises crickets at her pet store that she sells for reptile food. She thinks that crickets chirp more often when the temperature gets warmer. She decides to conduct an experiment. What should her hypothesis be?

Hypothesis Daniel notices that he catches more fish in a lake that is cooler than 55 degrees. While gathering information, he finds out that the cooler the temperature in a lake, the more oxygen the water holds. He wants to conduct a study so he can catch the most fish possible this year. He’s having trouble writing a hypothesis. Please help him.

Hypothesis You notice that your house plants beneath a mostly green stained glass window are not growing very well. You become curious about how the color of light will affect plant growth. Write a hypothesis regarding the what color of light (red, blue, or green) will help a plant to grow the tallest.

EXPERIMENT

Experiments have very stringent (strict) requirements to assure they are valid. The key to good science experimentation is: 1. Make sure the experiment fits the hypothesis. 2. That there is only one variable being tested. 3. That all other items in the experiment are controlled. (Control group and constants) 4. Use of large sample sizes to increase accuracy. 5. All data is recorded, analyzed and organized and the experiment (and results) are repeatable.

Variables: A variable can be either dependent or independent. Independent Affects the dependent variable. The treatment, what the experimenter is doing Graphed on the x axis Dependent Is affected by the independent variable The outcome, what is being measured Graphed on the Y axis

Think back to your hypothesis about plants and light color… In that scenario what would be a control group? Constants? IV? DV?

Mr. McNiece wanted to see how different types of music affected students' pulse rates. He played different types of music: heavy metal, rap, R&B, alternative, pop, country, and classical music and measured the pulse of 35 students. 1) Identify the independent variable. 2) Identify the dependent variable. 3) What constants would be needed for an experiment like this. 4) What could your control group be?

A test for the affect of amount of light on plant growth is done so growth in mm is collected every 2 days from plants both in the light directly and not in the light at all. 1) Identify the independent variable. 2) Identify the dependent variable. 3) Think of 3 constants that would be needed for an experiment like this. 4) What could your control group be? 5) Since this is the experiment, what steps occurred before this one?

Sample size The larger the sample size, the more accurate the experiment. Experiments done with very small sample sizes are statistically insignificant and should be thrown out.

ANALYZING DATA AND CONCLUSION

Graphing!! Once you have collected your data, part of analyzing is often creating a graph to you can notice trends, relationships, and overall understand what the data means. In science we will almost always use a LINE GRAPH or SCATTER PLOTS. Other types of graphs can be effective but they are rare.

How to set up your graph IV is on the x axis and DV is on the Y axis. Numbers must be evenly distributed across the axis, do not just copy your data table! Assume it is a line graph if there is any measurement of time involved. You must always label both axis and include units. You must always put a descriptive title on your graph. If there is more than one line, make a key. Your graph should take up all available space. Don’t make a tiny graph in the corner of your graph paper!

LET’S GRAPH!!! Woohoo!!

Temperature (c) Volume (mL)

LET’S GRAPH!!! Woohoo!! Temperature (c) Volume (mL) The effect of temperature on volume of a liquid.

In analyzing data while comparing the relationship between our dependent and independent variables, we can determine the relationships that the numbers (values) have. They will be…

Direct relationship (positive slope) Both X and Y values increase or both X and Y values decrease.

Indirect relationship negative slope) One variable is increasing and the other is decreasing.

Neutral relationship Y value stays constant over time. Indicates that the dependent variable is not affected by the independent variable.

Variables can be related Causation: One variable causes the other to change. Correlation: the variables both change but due to an unknown outside factor.

CONCLUSION

Conclusion You will determine if you hypothesis was supported or refuted. Give specific numerical data to support any claim that is made. If you reject your hypothesis, propose a new possible hypothesis to be tested in future experiments. Use reasoning to show how your data is all related and what trends you can see.

Theory Organized system of accepted knowledge that explains a phenomena Based on multiple supported hypotheses. Must be: – Logical – Peer reviewed – Public – Respectful of the rules of evidence

Scientific Law A relationship in nature that is supported by numerous experiments. It describes something known to happen without error, such as gravity, but does not explain how it happens It is up to the scientist to develop further hypotheses and experiments to explain WHY these relationships occur.

Pure Vs. Applied Science Pure Exact Science of producing scientific theories. There may be no practical usage Doing science for the sake of science Applied Used to come up with answers to problems Answers a question in the natural world Driven by the need to fix a problem or change something

Try These Development of String Theory Pharmaceutical research and drug testing Building different types of rocket engines in lab Using new rocket engines to travel farther into space