1. Improving Experiments

2. Constants  Constant - the things that stay the same in your experiment.  Independent Variable - The ONLY difference between the experimental group and the control group. This CANNOT be a constant!  This means that EVERYTHING else should be the SAME between your groups!

3. Constants: Example  If I wanted to test the affect of water temperature on plant growth, I would give one plant hot water, one plant cold water and my control group plant would get room temperature water.  What would I need to keep the same between the two groups?

4. Multiple Subjects  Testing multiple subjects makes an experiment more credible.  Subjects can be people, plants, animals, cars, etc.  In the previous example, would it be better to have 3 plants in each group or 100 plants in each group? Why?

5. Multiple Trials  Multiple trials also makes your experiment more credible  The more times the same experiment is repeated with the same results, the more your hypothesis is supported  Multiple trials are better because _____________________________

6. FIX THIS EXPERIMENT!  Jade heard that eating spinach makes you stronger. She gives her older brother spinach but doesn’t give any to her little sister. The next day she takes them both to the gym and records how much they each can bench press. Since her brother can bench press more, she decides her hypothesis is supported.

7. What Else Can Affect Your Experiment?  Bias  Credibility  Where’s the money  Can’t be replicated  Lack of hard data