A control variable is the factor that is kept the same on purpose throughout the entire experiment.
An inference is an idea formed from facts or evidence. Inferences that can be tested are called hypothesis. Scientific observations help scientist make inferences.
An observation is something you notice, measure, or detect. You make observations using your five senses. There are two types of observations in science, qualitative and quantitative. Scientific observations are based on facts, not opinions, feelings, or ideas.
Qualitative describes something using your five senses and can't be measured. Quantitative can be measured, but does not use the five senses.
The independent variable affects the change in the dependent variable. The dependent variable depends on the independent variable.
This is the scientific method. First you ask a question. Next you make a hypothesis. Then do the experiment. After that you observe the experiment. Next analysis it. Finally make a conclusion.