1. Scientific Method Making observations, doing experiments, and creating models or theories to try to explain your results or predict new answers form the essence of a scientific method. All scientists, including physicists, obtain data, make predictions, and create compelling explanations that quantitatively describe many different phenomena.

2. A scientist often works with an idea that can be worded as a hypothesis. A hypothesis is an educated guess about how variables are related. I have seen many variations in the steps of the scientific method. The one we will use has the following steps: Recognize a problem Make a hypothesis (predicted solution) Perform experiments to test prediction Analyze data Form a conclusion

3. The experiments and results must be reproducible; that is, other scientists must be able to recreate the experiment and obtain similar data. After performing your experiment many times with the same results, you can form a theory. A theory is a general conclusion about the validity of your hypothesis.

4. Sometimes scientists use models to help explain a hypothesis or theory. A model is a representation of a larger object or a theory that helps explain a concept. There are different types of models. Models can be two dimensional drawings, three dimensional structures, mathematical equations, animals, and computer representations are all types of models.

5. Even an idea can be a model. Scientific models are based on experimentation. If new data do not fit a model, both new data and model are re-examined. If a very well-established model is questioned, physicists might first look at the new data: Can anyone reproduce the results? Were there other variables at work?

6. If the new data are born out by subsequent experiments, the theories have to change to reflect the new findings. Here’s an example. In the nineteenth century, it was believed that linear markings on Mars showed channels. As telescopes improved, scientists realized that there were no such markings.

7. In recent times, again with better instruments, scientists have found features that suggest Mars once had running and standing water on its surface. Each new discovery has raised new questions and areas for exploration. A scientific law is a rule of nature that sums up related observations to describe a pattern in nature.

8. An observation is the act of noticing something through careful and direct attention. A qualitative observation is an observation of a trait or characteristic of something that is not an amount or number. A quantitative observation is an observation of the amount or number of something.

9. .An inference is a logical conclusion based on an observation or previous knowledge.