Scientific Method Mr. Jones 8 th Grade Science

What is the ‘scientific method’? The words Scientific Method are a term referring the principles that guide scientific research and experimentation. It is a process for solving problems and answering questions. Ways of thinking in science are called the process skills.

Steps in the Scientific Method The steps or process skills of the Scientific Method are typically: Observation Measurement Predicting Communication Experimentation

Scientific Method The process skills of the Scientific Method that are important for Physical Science are: Measurements & metric system Prediction Communication

We communicate when we give or receive information. It is basic to problem solving Related to lab results and data generated by your measurements.

Scientific Communication Scientists use data all the time Recording and organizing the data in a precise way is critical in communicating results and in formulating conclusions. Data tables and graphs are useful tools scientist use to communicate their data.

Communication Data – Information gathered by observation or experimentation that can be used in calculating or reasoning. Data tables- A way to organize data in columns so that it is neat and readable and can be analyzed.

Examples Length of Drop (cm) Height of Bounce (cm) Ball Bounce Test

Data Tables Rules Every data table has a ‘title’ so the reader can determine what the data refers to. Data tables contain variables and units. The variable describes what data you are recording. The units describe how you are going to measure it. Units are always in parenthesis and never inside a table cell. They appear in a column heading.

Graphs & Graphing Graphs are just a picture of information from a data table and visually show the relationships of that data. Three types – Line graphs Circle graphs Bar graphs

Graphs Line graphs – A graphing method useful for showing changes in variables over time. Circle graphs (pie charts)– A graphing method used only when data can be expressed as percentages of the whole. Bar graphs – A type of graph in which the lengths of the bars are used to represent and compare data. Typically used to show results that are one time & not continuous.

Circle Graph

Bar Graph

Line Graph

Variables Independent variable – the factor that you wish to test and that is altered so that it can be tested. Dependent variable – the factor that is observed to change in response to something. Ask yourself which one ‘depends’ on the other. If it does ‘depend’ then it is the dependent variable and the other is the independent variable.

Rules for making Line Graphs You will need graph paper, ruler, & pencil Draw all lines with a ruler. The independent variable is always written on the X axis (horizontal) and the dependent variable is on the Y axis (vertical). A line graph has a descriptive title, both axis labled correctly with the units of measurement and what is measured, data points plotted neatly, and a line connecting data points drawn with a ruler. Space numbers (scale) evenly along each axis of the graph.

Predicting A prediction is a forecast of what a future observation might be. Predictions are written in the future tense. Write a prediction in the form of an ‘if…., then…’ statement. Write the independent variable in the ‘if’ phrase, and the dependent variable in the ‘then’ phrase. Let’s practice…….

Independent vs. dependent Independent variable – it is the ‘manipulated’ variable or what you change in a scientific process. Dependent variable – it is the ‘responding’ variable or what you observe changing.

Making Predictions If pickles are kept cold, then they are crisper. What’s the independent variable and dependent variable? If you put more water on grass, then it will grow taller. What’s the independent & dependent variable?

Hypothesis If students use backpacks in higher grades, then their backpacks will be heavier, because they have more textbooks. If a tablet is placed in water and stirred, then the tablet will dissolve faster, because stirring increases the solution rate.

Hypothesis If students use backpacks in higher grades, then their backpacks will be heavier, because they have more textbooks. If a tablet is placed in water and stirred, then the tablet will dissolve faster, because stirring increases the solution rate.

Predictions & Experiments The purpose of experimenting is not to prove the prediction is correct. Rather, the purpose of experimenting is to support or not support the prediction. Excellent information is gained when your prediction is not supported.