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Stating the Problem Ideas for experiments usually come from making observations. An observation is information collected by using your senses. Fire is hot. Lemons are bitter. Observation: People that watch too much TV don’t do well in school. Let’s turn this observation into a question so that we can figure out how we could study it scientifically. Does watching too much TV rot your brain? This is called making a problem statement.
Take the observations below and turn them into questions. My dog drools at dinner time. The people who do their homework usually do well on the test. Stop and write down your answers before going to the next slide. Stating the Problem
My dog drools at dinner time. Does the smell of food make my dog drool? The people who do their homework usually do well on the test. Does doing your homework help you get good grades? How did you do? Your answers don’t have to match exactly. Stating the Problem
Making a Hypothesis Now that we have decided what we want to study, we have to make a hypothesis. A hypothesis is a prediction about the world that needs to be tested. It should be an: if…then… statement. For example, if you watch too much TV, then your brain rots.
Take the problem statements below and make them into hypotheses. Does eating too much candy make you sick? Does smiling at people make them nicer to you? Stop and write down your answers before going to the next slide. Making a Hypothesis
Does eating too much candy make you sick? If I eat too much candy, then I will get sick. Does smiling at people make them nicer to you? If I smile at people, then they will be nicer to me. How did you do? Your answers don’t have to match exactly. Making a Hypothesis
Sometimes people confuse observations and hypotheses. See if you can identify whether the statements below are observations or hypotheses. If I dye my hair purple, then people will like me more. Samantha has purple hair and is really popular. Making a Hypothesis
If you watch too much TV, then your brain rots The if part of the statement is the Independent Variable. I control the independent variable Amount of TV watched. The then part of the statement is the Dependent Variable. The dependent variable is measured. The amount of rot detected in the brain. Making a Hypothesis
Designing an Experiment Now that we have made a prediction (hypothesis) we can design our experiment. What should our experiment look like? We need to have people watch TV, and see what happens to their brains. Lets vary the amount of TV that they watch and measure their brain activity.
In a good experiment, your goal is to collect data. This determines if our hypothesis is supported or refuted. Data are groups of information. (Datum is one, Data is more than one). Data can be qualitative (descriptions) The older kids jumped farther than the younger kids. Data can be quantitative (numbers) 11 year olds long jump an average of 1.6 meters. Designing an Experiment
Your experiment should usually also have a control. A control is atrial that duplicates all conditions except the variable being investigated Example: In our experiment, we should measure the brain activity of people who don’t watch any TV. Designing an Experiment
Designing an Experiment Scientists want their data to be both accurate and precise. Accuracy Close to the true or desired value Precision Reproducible measurements
Analyzing the Data Now that we have collected our data, we need to analyze it, or see what it means.
No experiment is perfect, and our results can be effected by mistakes and errors. Mistakes – Caused by the scientist, can be prevented by being careful. Errors – Caused by experimental design or equipment. Much harder to prevent. Analyzing the Data
What is wrong with our experiment? What type of TV Programs were watched? Does less activity mean your brain is being ‘rotted’? Analyzing the Data
Now, we do the experiment again keeping our errors in mind. What would a new experiment look like? Analyzing the Data