You'll widen your theoretic background and gain confidence with difficult exercises. Often the problem or need for extra science classes is a lack of self confidence or a lack of feeling comfortable with the study material. Especially when the exams are approaching and the volume of the study material increases it is important that you can make the study material less abstract and meaningful to feel comfortable. I have lots of experience with this process. I am a master in engineering and data scientist with more than 10 years of experience with tutoring math and sciences.