1. A good scientific question is one that can have an answer and be tested. "Why is that a rock?" is not as good a question as "What are rocks made of?" 2. A good scientific question can be tested by some experiment or measurement that you can do. In this case "Where does the Sun come from?" is not as good as, "How will human skin, covered with SPF 30 suntan lotion, react to solar radiation compared to skin not covered with suntan lotion?" 3. A good scientific question builds on what you already know. "Will fertilizer make grass grow greener?" is not as good as, "What types of fertilizer will make grass grow greener and not cause harm to the environment?" 4. A good scientific question, when answered, leads to other good questions. "What is HIV?" does not lead to as many other questions as, "How does the HIV virus cause the human immune system to malfunction? The questions above ask What and How in a way that focuses in on the specific problem to be studied. These questions frame a problem in a way that can be tested. For example, an example of a good scientific question about salmon might be: "What is causing the forest bordering the streams to be unhealthy and no longer support salmon runs?"