Some days you'll be bolting this together, or turning that on, reading papers, sitting and thinking. . . . You may have 20 pages of a paper filled with equations and you need to analyze all of it and understand what's in it. Another day you may be engrossed in how well an apparatus did or did not work. The question of that or which, the amateur grammar that we're not always too great at necessarily. By doing it as an undergraduate.
Most undergraduate programs get students into labs working on experiments.
Many of these may be classic great experiments such as the Millikan oil drop when you conduct the measurement of an electrical charge. As juniors and seniors there are required experiments using some level of real science inquiry while at the same time you have to get through those thick books and those exams. I attended Massachusetts Institute of Technology for my undergraduate degree and the University of Wisconsin-Madison for graduate school. I remember MIT as brutal, but graduate school was really great. After MIT I did a stint as an engineer at Control Data and Varian and Associates.