Scientific Method What is the scientific method? • It is a way in which scientists answer and solve problems • The steps to solve a problem or question Steps of the scientific method 1. State problem or question to be solved or answered 2. Form a hypothesis 3. Experiment to test hypothesis 4. Collect data from experiment and observations 5. Form a conclusion 6. Communicate ideas and results Use observations to form a question you would like to investigate • You can use your senses to gather information. – _______________ observation Qualitative • You can use tools to gather information called measurements Quantitative – _______________observation – Tools make accurate observations. • Often you are asking a question about the relationship between things • Example: The position of the light source and the size of the shadow Hypothesis • A possible explanation that needs to be tested • “If…….., then………. will happen. • Form a hypothesis about the position of the light source on the object and the length of the object’s shadow. If the light source gets closer to the object, then the objects’ shadow will get… • Hypotheses are NOT facts! Instead it is a possible way to answer a question. • Many trials are needed before a hypothesis can be accepted as true. Experiment • When you carry out procedures to test your hypothesis • Experiments begin by first examining all the variables • Variables are factors that can change in an experiment – Can you name a few variables that could change in an experiment? • Experiments should be designed so only one variable is changed! • There are two types of variables: Independent variable and dependent variable Independent Variable • The variable that is changed in an experiment – Example: Susan sets up an experiment to test whether the position of the light impacts the length of the shadow. In order to test this, she shines the light on a cereal box from six different positions. At each position, she measures the length of shadow the cereal box casts. What would be the independent variable? (Hint what is Susan changing?) The position of the light Dependent Variable • The variable that is expected to change because of the independent variable. – Example: Think about Susan’s experiment to test whether the position of the light impacts the length of the shadow. She shown the light on a cereal box from six different positions, and at each position, she measured the length of shadow the cereal box casts. What is the Dependent variable? (Hint: what is changing because of Susan’s independent variable?) The length of the shadow Identify the Dependent and Independent Variables. • Students conduct an experiment to test if studying leads to higher tests scores. What would be the independent variable (the thing that changes)? What would be the dependent variable (What is changing because of the independent variable)? Independent Variable: Time spent studying Dependent Variable: Test score Identify the Independent and dependent variable • A scientist conducts an experiment to test the theory that a vitamin could extend a person’s life-expectancy – What would be the independent variable? – What would be the dependent variable? Independent Variable: Taking Vitamins Dependent Variable: Life-expectancy (How long you live) Identify the independent and dependent variables. • Students experiment to see how different amounts of sunlight impact how much plants grow. – What would be the independent variable? – What would be the dependent variable? Independent Variable: Amount of sunlight Dependent Variable: Plant growth Control Group and Experimental Group • A control group is a group in a scientific experiment where no variables are changed. • It is used to compare results against the a group where a variable is changed called an experimental group. – Example- A student is testing to see if plants will grow without sunlight. • Which would be the experimental group and which would be the control group? Control Experimental What makes a good experiment: • Control group • One independent variable • Testing the hypothesis many times (many trials) Collecting and Interpreting Data • Make observations and record them into a data table. • Data tables can be for both quantitative and qualitative observations. – Make a data table that would describe some qualitative observations of different types of rocks – Make a data table that would describe some quantitative observations of different types of rocks. • Graphs are useful way to view quantitative data because they reveal trends or patterns Explain the graph Explain the graph Explain the graph Drawing Conclusions • After scientists interpret their data (with the help of a graph usually), they draw a conclusion about their hypothesis. • Conclusions state whether or not the data supports the hypothesis – My hypothesis was correct because…. – My hypothesis was incorrect because… Should be supported by observations!!! Communicating • Sharing ideas and conclusions about your experiment with others through writing and speaking • Scientists share the design of an experiment as well so others can repeat the experiment to check the results • Communicating information about discoveries often leads to new questions, new hypotheses, and new investigations. Model • Represents an object or system in science. – Example: Globe of Earth Theory • A well tested explanation for many observations and experimental results. • Well tested and widely accepted by scientists. – Example: Atomic theory- all substances are composed of tiny particles called atoms. This theory explains many observations: why water freezes or boils at certain temperature, and why water can dissolve many other materials Law • A statement that describes what scientists expect to happen every time under a particular set of conditions – Example- Law of Gravity “What goes up must come down.” • A scientific law describes an observed pattern in nature without attempting to explain it.