Science classes are most common way the people study the sciences. Some of the main problems with science classes are the lack of individual attention that the participants receive.
People who study science in a class environment can miss out on important details either through not hearing the teacher properly or not understanding the meaning of a specific scientific term. A lot of students don't feel able to ask questions in a class environment and let the issue slide. Missing out on tiny bits of information isn't generally all that important but sometimes that bit of information can be key to understanding something else and before you know it the student is failing the class.
Science classes can also be disruptive with many other influences and distractions detracting from the lesson. Surveys have shown that having a private science tutor consistently boosts grades, confidence and understanding of the subject.