I.V. is the factor that the scientist changes on purpose. The D.V. is the factor that changes as a result, often measured. A control variable is the factor that is kept the same on purpose.
A qualitative observation you use your five senses smell, taste, touch, hearing, and sight. A quantitative observation is when you measure something like height an weight. An inference is an opinion or guess.
First you make a qualitative or quantitative observation. Next you ask a question about you observation. Then you make a hypothesis which is what you believe is going to happen. After that, you experiment or test your hypothesis. Then you record data or make notes, pictures, charts, and even graphs. Last you make a conclusion it involves analyzing and summarizing the results.