1. Designing a Scientific Test A test is where a scientist gathers data. In a comparison test, everything you do to one experimental group must be exactly the same as you do to the other group (control group). The one different factor is called the variable. In our tests, we want to collect measureable results QUESTION: Does adding earthworms to a potted plant make it grow taller than a regular potted plant? Control Group Regular Potted Plant Experimental Group Potted Plant with Earthworms Variable Constants same size pot same soil same amount of water same sunlight All of the other factors, which are the same for both groups, are called the constants.

2. Controlled Experiments Vocabulary Controlled Experiment : an experiment where the scientist compares the thing they want to test to something they already know about control group : the part of the experiment that you know about and can use to compare to the thing you want to investigate experimental group : the part of the experiment that has the thing you want to investigate c.g. v. e.g. + =

3. generally the thing that you are curious about investigating Controlled Experiments, cont. variable : the one thing that is different between the control group and the experimental group constants : the things in your experiment that you keep exactly the same the only thing in an experiment that is different between the control group and the experimental group is the variable the variable is usually part of the experimental group

4. Controlled Experiment Examples I began to think that my plants would grow bigger if I used fertilizer. Fertilizer is supposed to give plants more nutrients so it should help them to grow. Question: Will plants fertilized with Frank’s Fabulous Fertilizer grow bigger than a regular plant? c.g. Regular Plant e.g. Regular Plant with Frank’ Fabulous Fertilizer + v. F.F. Fertilizer =

5. Controlled Experiment Examples I do not like moldy bread. My regular bread gets moldy in 5 days. I want to find a bread that does not get moldy so quickly. Question: Will whole wheat bread get moldy faster than my regular bread? c.g. Regular Bread e.g. Whole Wheat Bread + v. type of bread =

6. Controlled Experiment Examples I am so hot and thirsty! I want a home-made popsicle, and soon! Should I put sugar in the flavored water to make it freeze faster? Question: Does sugar water freeze faster than just plain water? c.g. Plain Water e.g. Plain Water with Sugar added + v. Sugar =

7. Controlled Experiment Examples I want some apple, but not a whole one. What would happen if I just took one bite from one? Question: Does an apple with one bite taken out rot faster than a whole apple? c.g. Whole Apple e.g. Apple with Bite Taken Out + v. One Bite! =