The Scientific Method

The Scientific Method Definition: A series of steps that scientists use to answer questions and solve problems. What kinds of questions can be answered? Is it possible to clone an animal? Yes How many pounds of tomatoes does an average person eat in a year? 30, mostly in ketchup If you mate a purple flowered pea plant with a white flowered pea plant, what will the offspring look like? For every 4 new plants, 3 will be purple and 1 will be white

What are the steps of the scientific method? Ask a question based on observations Make observations with your 5 senses (See, hear, smell, taste, touch) Ask a question about what you observed What do you want to find out?

What are the steps of the scientific method? Form a hypothesis is a possible answer or explanation. You must be able to test it with an experiment. Written in “If…, then ...” format.

What are the steps of the scientific method? Prepare materials for your experiment & set up Control Group: group you don’t experiment with Independent variable: variable you can control changes to Dependent variable: variable you cannot control changes to

What are the steps of the scientific method? Do an experiment with procedures / steps to test the hypothesis

What are the steps of the scientific method? Record your observations/data/results Put data into a chart or graph. Organize data so others can read it easily.

What are the steps of the scientific method? Analyze the results Explain:How? Why? What?

What are the steps of the scientific method? Draw conclusions Was your hypothesis correct or incorrect? What did you learn anything from the results?

Ask a question based on observations. Make observations with your 5 senses (See, hear, smell, taste, touch) Ask a question about what you observed (What do you want to know?) I observed that lots of people take cough medicine when they have a cough. That made me wonder: Does cough medicine make a cough go away faster?

Form a hypothesis A hypothesis is a possible answer or explanation. You must be able to test it with an experiment. Written in “If…, then ...” format. If cough medicine really works, then people who take cough medicine will get better faster than people who do not take cough medicine.

Do an experiment to test the hypothesis. List all materials you need. Write a detailed list of instructions. Make a data table to record data. Perform the experiment. I talked to 100 students at my school. I asked 50 to take cough medicine next time they got a cough, and I asked 50 NOT to take any cough medicine next time they got a cough. I interviewed each student after he/she was better, and wrote down in a data table the number of days the cough lasted.

Analyze the results Put data into a chart or graph. Organize data so others can read it easily.

Draw Conclusions Was your hypothesis correct or incorrect? What did you learn from the results? My hypothesis was incorrect. I hypothesized that cough medicine would make coughs go away faster. My results show that it took slightly less time for a cough to go away when the person did NOT take cough medicine. The results were so close together that I think there was no real difference between people who took medicine and people who did not. I learned that taking cough medicine does not help a cough go away faster.

What to do if your hypothesis is wrong... Form a new hypothesis! You do not have to ask a new question or design a new experiment. Just redo the same experiment with a different hypothesis. Remember: The steps of the scientific method are not always followed in order. It’s all right to skip some and redo others. Don’t cry! Just because your hypothesis was wrong does not mean you did your experiment wrong.

Sources of error Measuring error (did not measure carefully) Materials error (got the wrong material) Too small sample size (interviewed 20 people instead of 2000) Testing too many variables at one time (medicine or not, type of medicine, amount of medicine). Only test one variable at a time!