One of my biggest pet-peeves is the misuse of the terms Theory and Law.
A scientific theory is an attempt to explain an observation or occurrence. It must be well-tested and supported by experiments to be considered a theory, so this does NOT mean that a theory is untrue!!!
A scientific law is a description of an observation or occurrence. It does not attempt to explain, rather is just describes something.
Click the button above to link to a TedEd blog that further discusses the difference between these two often misused terms.
Steps of the Scientific Method and Controlled Experiments
The picture above is Figure 2-9 from page 48 of your book. To help you further understand the scientific method and the purpose of controls in experiments there is a great playlist from Khan Academy that explains this through a biology class perspective. Check it out by clicking the Khan Academy picture to the right.