Aim: How can we design experiments? Do Now: You will be designing an experiment to test the effect bleach has on colored water. Group A :1. Explain the difference between an independent and dependent variable 2. Develop a question for this experiment Group B: Create a hypothesis for the experiment.

Design an experiment to test the effect of bleach on colored water Add a “ What is” to develop your question Then create a statement to answer your question, try to use the IF and Then- HYPOTHESIS

Controlled Experiment Must have only one independent variable Must have a control and an experimental group CONTROL GROUP: EXPERIMENTAL GROUP: INDEPENDENT VARIABLE DEPENDENT VARIABLE

What conclusion can you draw? Does it support or refute your hypothesis?

Can you redesign this experiment with more than one cup for the experimental group? Why would you do this? What kind of data would this lead to?

DATA 2 ounces of bleach4oz. Of bleach6 oz. of bleachNo Bleach COLOR Amount of Bleach Added to Water There is still only one independent variable but you just changed the experiment a bit- you can retest with the same independent variable just a bit differently.

In what ways can we make the experiment more VALID? Valid- to be accurate or correct Repeating the experiment Only one independent variable for each experiment Everything else except the independent variable must be held constant- same amount of water, same water temperature Large sample size – testing many subjects

Biological Experiments Experimental and Control groups are most often living organisms- Identify some living organisms that might be test subjects What are some independent variables that are used to see what effect they have on the organisms? Sunlight Water Acid or Acid Rain Exercise Food