Qualitative means that you observe using your 5 senses. Quantitative mean that you observe using measurements. An example for qualitative is the dogs ears are long, a quantitative one can be the dogs ears are 4 in.
Observations and inferences are two completely different things. An observation you use your 5 senses. For an inference its like your own opinion based on the observations.
The 3 variables are independent dependent variables. the independent variable is what I change in the experiment. the dependent variable is what i observe during the experiment. the control variable is the variable is what i keep the same through out.
The scientific method contains 6 steps. The first step is to find a problem. The next step is to find out about your topic. The 3rd step is to make a hypothesis, make an educated guess about whats going to happen. 4th you conduct an experiment. 5th you collect and analyze your data. last but not least u come up with an experiment.