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​Developing a Hypothesis

• Hypothesis : a possible answer to a scientific question

  • What you think might answer the question

  • NOT a fact, simply a possibility

  • A hypothesis has to be something you can test

    • If you can't test it, you need to re write it

  • Written as an If....Then Statement

    • If I do one thing, then another will happen in response

Grade 8 | Chapter 1.3

​How do you Design an Experiement?

• Once you have a hypothesis you can design an experiment that follows scientific principles

  • You first need to define Variables, or different parts of the experiment

    • Independent Variables: the part of the experiment that you are testing

      • Example: The scientists changed where they grew the two sets of potato plants

    • Dependent Variable: Every thing else in the experiment

      • Has to stay the same between different samples

Grade 8 | Chapter 1.3

​Designing a Controlled Experiement

• A Controlled Experiment only tests one variable at a time

  • Makes it easy to know what variable influenced the results

    • If the scientists grew their potatoes in space and on Earth, but used different amounts of water when they planted, how do they know being in space is what caused the changes in the plants

• Every Experiment runs the risk of Experimental bias, or an error that makes one result more likely

  • It is always important to check and make sure that you are not doing anything that may influence the results​

  • Having multiple Variables may introduce Bias

Grade 8 | Chapter 1.3

​Collecting and Interpreting Data

• Data can take the shape of many different formats. Depending on your experiment, you may want to use some more than others to see different patters

  • Data Table: A chart used to organize numerical data in a concise way

  • Graph:​ a chart that can be used to compare how a result changes when the independent variable changes

  • Pie chart: Used to compare amounts or percentages of something

Grade 8 | Chapter 1.3

​Drawing Conclusions

• A conclusion is a summary of what you learned from your experiment

  • You look at the data objectively to see if the results support or fail your hypothesis

    • rejecting your hypothesis is not a failure, but allows you to learn something new

      • Can allow you to eliminate options in complex systems

    • sometimes your results may be unclear, and you can neither support nor reject your hypothesis

  • Explaining the pattern in a way that doesn't use numbers​

• Conclusions based on one single experiment are not reliable, because you can't 100% control everything

  • A repeated trial is a repetition of an experiment

    • Can happen after your first experiment, or at the same time​

​Communicating

• Scientists share their ideas with others in a variety of ways

  • through journal articles, sending each other information on the internet, sending videos of results

• When scientists send their results to another person, they explain everything they did to the other person so they can perform the experiment

  • Replication: an attempt by a different group of scientists to conduct the same experiment

    • Helps to make sure the results and conclusions drawn are correct, and can also lead to new ideas or improvements in the experiments

Scientific Explanations

• Some studies can't be done using controlled experiments, so they rely on scientists making a scientific explanation

  • a generalization based on observations and logical reasoning

  • Things that are very big

    • Space, ecosystems

  • Things that are very small

    • Cells in your body

Grade 8 | Chapter 1.3